Steve Hinder

Dr Steven Hinder

Experimental Officer, Manager of the Surface Analysis Laboratory
+44 (0)1483 689624
23 AB 03

Academic and research departments

School of Mechanical Engineering Sciences.


Joseph Paul Baboo, Ewa Jakubczyk, Mudasir A. Yatoo, Matthew Phillips, Sean Grabe, Matthew Dent, Steven J. Hinder, John F. Watts, Constantina Lekakou (2023)Investigating battery-supercapacitor material hybrid configurations in energy storage device cycling at 0.1 to 10C rate, In: Journal of power sources561 Elsevier

Battery-supercapacitor hybridisation enables safe charge-discharge operation at high C rate, up to the supercapacitor capacity, while maintaining battery lifetime. However, battery-supercapacitor systems in parallel connection require a DC/DC converter for voltage balance. Hybridisation at material level is explored in this study aiming to avoid the use of a DC/DC converter. Different battery-supercapacitor configurations, hybridised at material level, are investigated with the goal to maintain the long redox plateau of the battery and to self-balance without the need of DC/DC converter. Applying these principles to a LiFePO4 (LFP) battery, the best configuration was found to be a device with a Li anode and a composite LFP/activated carbon (AC) cathode reaching 180 mAh per gram of battery cathode. The device is cycled according to different schedules from 0.1C to 10C rate and the cathode and anode surface are characterised microstructurally and in terms of their chemical composition, after just fabricated and post-mortem after cycling according to different C rate schedules.

G.I Siakavelas, N.D Charisiou, S AlKhoori, A.A AlKhoori, V Sebastian, S.J Hinder, M.A Baker, I.V Yentekakis, K Polychronopoulou, M.A Goula (2021)Highly selective and stable nickel catalysts supported on ceria promoted with Sm2O3, Pr2O3 and MgO for the CO2 methanation reaction, In: Applied Catalysis. B, Environmental282 Elsevier B.V

[Display omitted] •Microwave assisted sol gel method produces selective CO2 methanation Ni catalysts.•The incorporation of Sm3+ and Pr3+ into the CeO2 lattice generates basic positions.•Sm3+ and Pr3+ oxygen vacancies suppress the agglomeration of Ni sites.•Presence of Mg2+ increases basicity and prevents Ni sintering during reaction.•Ni on Pr-Ce highly active, selective and stable for CO2 methanation reaction. The present work reports on the investigation of the catalytic performance for the methanation of CO2 over Ni catalysts based on CeO2, and for the first time, of Ni catalysts supported on binary CeO2-based oxides, namely, Sm2O3-CeO2, Pr2O3-CeO2 and MgO-CeO2. The supports were obtained using the microwave assisted sol-gel method under reflux, while the catalysts were prepared by the wet impregnation method. For the investigation of the morphological, textural, structural and other intrinsic properties of the catalytic materials a variety of characterization techniques were used, i.e., Raman spectroscopy, XRD, N2 physisorption-desorption, CO2-TPD, H2-TPR, H2-TPD, XPS and TEM. Carbon deposition and sintering were investigated using TEM. It was shown that the addition of Sm3+ or Pr3+, incorporated into the lattice of CeO2, generated oxygen vacancies, but the Ni/Pr-Ce catalyst was found to possess more surface oxygen vacancies (e.g. Ce4+-Ov-Pr3+ entities). Moreover, modification of CeO2 using Sm3+ or Pr3+ restricted the agglomeration of nickel active sites and led to the genesis of Lewis basic positions. These characteristics improved the hydrogenation reaction at lower temperature. On the other hand, the addition of Mg2+ resulted at strong metal support interactions reinforcing the resistance of the Ni/Mg-Ce catalyst against sintering. Furthermore, the addition of Sm3+, Pr3+ and Mg2+ cations increased the overall basicity and the moderate adsorption sites and led to the formation of smaller Ni nano particles; these physico-chemical properties enhanced the CO2 methanation reaction. Finally, the activity experiments (WGHSV = 25,000 mL g−1 h−1, H2/CO2 = 4:1, T =350 °C) showed that at lower reaction temperature the Ni/Pr-Ce had the highest catalytic performance in terms of CO2 conversion (54.5%) and CH4 yield (54.5%) and selectivity (100%). The TOF values were found to follow the order Ni/Pr-Ce >> Ni/Mg-Ce > Ni/Sm-Ce > Ni/Ce.

M. Abi Jaoude, Emad Alhseinat, K. Polychronopoulou, G. Bharath, Ismail Farouq Fahmi Darawsheh, Shoaib Anwer, Mark A. Baker, Steven J. Hinder, Fawzi Banat (2020)Morphology-dependent electrochemical performance of MnO2 nanostructures on graphene towards efficient capacitive deionization, In: Electrochimica Acta330135202 Elsevier

Capacitive deionization (CDI) is an emerging desalination technology that still needs further development to enhance its performance for practical implementation. Herein, we present a hybrid CDI approach, which integrates the electrical double-layer (EDL) with the sodium-ion battery concept to improve the separation of sodium and chloride ions from saline water. The hybrid CDI cell is achieved by using hydrothermally-grown and uniformly dispersed prawn-like α-MnO₂/graphene (α-MnO₂/G) nanocomposite as anode material, and graphene at the cathode. In this paper, the effect of MnO₂ morphology on the electrode electrochemical performance and its effect on capacitive deionization performance have been fully investigated. In this configuration, the Na⁺ ions are inserted by the electrochemical reaction at the α-MnO₂/G electrode, whereas Cl⁻ ions are captured by the graphene-based electrode. The morphological dependent electrochemical properties of the obtained nanocomposites were studied deeply through CV and EIS analysis. The established hybrid CID cell provides an electrical capacitance as high as 375 F g⁻¹ at 10 mV s⁻¹, cation-selectivity, good electrical stability and low internal resistance. The hybrid CDI device also shows a stable and reversible salt insertion/de-insertion capacity up to 29.5 mg g⁻¹ at 1.2 V. These results demonstrate the suitability of prawn-like α-MnO₂/G nanocomposite to produce high-performance hybrid CDI cells.

Anastasios I. Tsiotsias, Nikolaos D. Charisiou, Victor Sebastian, Safa Gaber, Steven J. Hinder, Mark A. Baker, Kyriaki Polychronopoulou, Maria A. Goula (2022)A comparative study of Ni catalysts supported on Al2O3, MgO–CaO–Al2O3 and La2O3–Al2O3 for the dry reforming of ethane, In: International journal of hydrogen energy47(8)pp. 5337-5353 Elsevier Ltd

CO2 utilization through the activation of ethane, the second largest component of natural and shale gas, to produce syngas, has garnered significant attention in recent years. This work provides a comparative study of Ni catalysts supported on alumina, alumina modified with CaO and MgO, as well as alumina modified with La2O3 for the reaction of dry ethane reforming. The calcined, reduced and spent catalysts were characterized employing XRD, N2 physisorption, H2-TPR, CO2-TPD, TEM, XPS and TPO. The modification of the alumina support with alkaline earth oxides (MgO and CaO) and lanthanide oxides (La2O3), as promoters, is found to improve the dispersion of Ni, enhance the catalyst's basicity and metal-support interaction, as well as influence the nature of carbon deposition. The Ni catalyst supported on modified alumina with La2O3 exhibits a relatively stable syngas yield during 8 h of operation, while H2 and CO yields decrease substantially for Ni/Al2O3. [Display omitted] •Ni catalysts on Al2O3 modified with MgO/CaO and La2O3 for the DER reaction.•Modification of Al2O3 improves the catalyst basicity and metal-support interaction.•Extensive ethane cracking into CH4 takes place during the first 3–4 h.•Ni/La–Al2O3 is the most active and stable with H2 and CO yields remaining constant.•Modification of Al2O3 aids the coke gasification and reduces catalyst degradation.

Saoirse Dervin, Eugen Panaitescu, Latika Menon, Steven S. Hinder, Suresh C. Pillai, Mary Garvey (2020)In vitro pulmonary toxicity of thermally processed titania nanotubes, In: Journal of nanoparticle research : an interdisciplinary forum for nanoscale science and technology22(1) Springer Nature

The current study examined the in vitro pulmonary toxicity of titania nanotubes induced by the morphological and crystalline changes associated with post-synthetic thermal processing. A549 lung carcinoma cells were exposed to untreated, amorphous titania nanotubes and those treated at 200, 400, 600 and 800 degrees C, respectively. The cytotoxic action of the untreated and annealed TNTs was assessed using a battery of cytotoxicity assays that examined cellular metabolic and prolific activity and membrane integrity, in addition to the production of intracellular reactive oxygen species (ROS). Toxicity effects due to the period and dose of exposure were determined by exposing the A549 cell line to various TNT concentrations during different incubation periods. The untreated, amorphous and annealed TNTs elicited an overall dose-dependent increase in toxicity. As the annealing temperature increased from 200 to 800 degrees C, the nanotubular structure of TNTs fragmented and a crystalline phase composition developed. Crystalline nanoparticles also began to grow among the walls of disintegrated TNTs, and crystallite and particle size increased progressively. In comparison to amorphous TNTs, those of anatase, rutile or anatase/rutile mixed-phase composition exerted notable in vitro pulmonary toxicity. Rutile-rich TNTs possessing fragmented nanotube walls and larger particle size induced the greatest loss in viability of A549 lung carcinoma cells, presumably due to the domination of the rigid rutile crystal arrangement. The current study thus highlights the necessity for material manufacturers to consider the effects of post-synthetic processing on the possible toxicity profile of nanomaterial containing products and devices.

Abdul Khayum Mohammed, Safa Gaber, Jésus Raya, Tina Skorjanc, Nada Elmerhi, Sasi Stephen, Pilar Pena Sánchez, Felipe Gándara, Steven J Hinder, Mark A Baker, Kyriaki Polychronopoulou, Dinesh Shetty (2023)Crystallizing covalent organic frameworks from metal organic framework through chemical induced-phase engineering, In: Scientific reports13(1) Nature Publishing Group

The ordered porous frameworks like MOFs and COFs are generally constructed using the monomers through distinctive metal-coordinated and covalent linkages. Meanwhile, the inter-structural transition between each class of these porous materials is an under-explored research area. However, such altered frameworks are expected to have exciting features compared to their pristine versions. Herein, we have demonstrated a chemical-induction phase-engineering strategy to transform a two-dimensional conjugated Cu-based SA-MOF (Cu-Tp) into 2D-COFs (Cu-TpCOFs). The structural phase transition offered in-situ pore size engineering from 1.1 nm to 1.5–2.0 nm. Moreover, the Cu-TpCOFs showed uniform and low percentage-doped (~ 1–1.5%) metal distribution and improved crystallinity, porosity, and stability compared to the parent Cu-Tp MOF. The construction of a framework from another framework with new linkages opens interesting opportunities for phase-engineering.

Xinnan Lu, Safa Gaber, Mark A. Baker, Steven J. Hinder, Kyriaki Polychronopoulou (2021)Metal-Free Phosphated Mesoporous SiO2 as Catalyst for the Low-Temperature Conversion of SO2 to H2S in Hydrogen, In: Nanomaterials (Basel, Switzerland)11(9) MDPI

Highly active metal-free mesoporous phosphated silica was synthesized by a two-step process and used as a SO 2 hydrogenation catalyst. With the assistance of a microwave, MCM-41 was obtained within a 10 min heating process at 180 °C, then a low ratio of P precursor was incorporated into the mesoporous silica matrix by a phosphorization step, which was accomplished in oleylamine with trioctylphosphine at 350 °C for 2 h. For benchmarking, the SiO 2 sample without P precursor insertion and the sample with P precursor insertion into the calcined SiO 2 were also prepared. From the microstructural analysis, it was found that the presence of CTAB surfactant was important for the incorporation of active P species, thus forming a highly dispersed, ultrafine (uf) phosphate silica, (Si-P) catalyst. The above approach led to the promising catalytic performance of uf-P@meso-SiO 2 in the selective hydrogenation of SO 2 to H 2 S; the latter reaction is very important in sulfur-containing gas purification. In particular, uf-P@meso-SiO 2 exhibited activity at the temperature range between 150 and 280 °C, especially SO 2 conversion of 94% and H 2 S selectivity of 52% at 220 °C. The importance of the CTAB surfactant can be found in stabilizing the high dispersion of ultrafine P-related species (phosphates). Intrinsic characteristics of the materials were studied using XRD, FTIR, EDX, N 2 adsorption/desorption, TEM, and XPS to reveal the structure of the above catalysts.

Nikolaos D. Charisiou, Savvas L. Douvartzides, Georgios Siakavelas, Lazaros Tzounis, Victor Sebastian, Vlad Stolojan, Steven J. Hinder, Mark A. Baker, Kyriaki Polychronopoulou, Maria A. Goula (2019)The Relationship between Reaction Temperature and Carbon Deposition on Nickel Catalysts Based on Al2O3, ZrO2 or SiO2 Supports during the Biogas Dry Reforming Reaction, In: Catalysts9(8) Mdpi

The tackling of carbon deposition during the dry reforming of biogas (BDR) necessitates research of the surface of spent catalysts in an effort to obtain a better understanding of the effect that different carbon allotropes have on the deactivation mechanism and correlation of their formation with catalytic properties. The work presented herein provides a comparative assessment of catalytic stability in relation to carbon deposition and metal particle sintering on un-promoted Ni/Al2O3, Ni/ZrO2 and Ni/SiO2 catalysts for different reaction temperatures. The spent catalysts were examined using thermogravimetric analysis (TGA), Raman spectroscopy, high angle annular dark field scanning transmission electron microscopy (STEM-HAADF) and X-ray photoelectron spectroscopy (XPS). The results show that the formation and nature of carbonaceous deposits on catalytic surfaces (and thus catalytic stability) depend on the interplay of a number of crucial parameters such as metal support interaction, acidity/basicity characteristics, O2- lability and active phase particle size. When a catalytic system possesses only some of these beneficial characteristics, then competition with adverse effects may overshadow any potential benefits.

Mozhgan Yavari, Xueping Liu, Thomas Webb, K D G Imalka Jayawardena, Yuren Xiang, Stefanie Kern, Steven Hinder, Thomas J Macdonald, S Ravi P Silva, Stephen J Sweeney, Wei Zhang (2021)A synergistic Cs2CO3ETL treatment to incorporate Cs cation into perovskite solar cells: Via two-step scalable fabrication, In: Journal of Materials Chemistry C Materials for optical and electronic devices9(12)pp. 4367-4377 Royal Society of Chemistry

Triple cation CsFAMA perovskite films fabricated via a one-step method have recently gained attention as an outstanding light-harvesting layer for photovoltaic devices. However, questions remain over the suitability of one-step processes for the production of large-area films, owing to difficulties in controlling the crystallinity, in particular, scaling of the frequently used anti-solvent washing step. This can be mitigated through the use of the two-step method which has recently been used to produce large-area films via techniques such as slot dye coating, spray coating or printing techniques. Nevertheless, the poor solubility of Cs containing salts in IPA solutions has posed a challenge for forming triple cation perovskite films using the two-step method. In this study, we tackle this challenge through fabricating perovskite films on a caesium carbonate (Cs2CO3) precursor layer, enabling Cs incorporation within the film. Synergistically, we find that Cs2CO3 passivates the SnO2 electron transport layer (ETL) through interactions with Sn 3d orbitals, thereby promoting a reduction in trap states. Devices prepared with Cs2CO3 treatment also exhibited an improvement in the power conversion efficiency (PCE) from 19.73% in a control device to 20.96% (AM 1.5G, 100 mW cm−2) in the champion device. The Cs2CO3 treated devices (CsFAMA) showed improved stability, with un-encapsulated devices retaining nearly 80% efficiency after 20 days in ambient air.

Revathi Kottappara, Shajesh Palantavida, Steven J. Hinder, Suresh C. Pillai, Baiju Kizhakkekilikoodayil Vijayan (2020)New synthesis route of Cu-CuO-Ni nano-heterostructures for hydrogenation and chromium reduction reactions, In: Journal of environmental chemical engineering8(1) Elsevier Ltd

[Display omitted] •Novel strategy for the synthesis of hetero structured Cu-CuO-Ni nanocrystals.•Reduction of p-nitrophenol and of chromium (VI) was explored.•An activity factor of 0.0088 s−1 mg−1for reduction of 4-nitrophenol was observed.•The rate constant value for chromium reduction reaction was 0.057 min−1. A simple one-pot aqueous phase chemical reduction has been used for the successful synthesis of flower-like Cu-CuO-Ni heterostructures. X-ray diffraction analysis and X-ray photoelectron spectroscopy confirms the presence of metallic copper, nickel and monoclinic copper oxide (CuO) in the sample with traces of Cu(OH)2. Scanning electron microscope images confirms the flower like morphology of the Cu-CuO-Ni nanoheterostructures. For the first time, Cu-CuO-Ni nanocrystals were employed as a new heterogeneous efficient nanocatalyst for the hydrogenation reduction of 4-nitrophenol (4-NP) and reduction of chromium (VI) (Cr) to chromium (III). The synthesized Cu-CuO-Ni nanocrystals showed highest catalytic properties with an activity factor of 0.0088 s−1 mg−1for reduction of 4-nitrophenol and 0.057 min−1for chromium reduction reaction. The XRD and XPS analysis of the catalytically recycled samples suggests the higher catalytic stability of Cu-CuO-Ni nanocrystals. In comparison to the bare CuO and CuO- Ni nanocrystals the maximum catalytic activity was shown by Cu-CuO-Ni nanocrystals. The improved catalytic activity was found to be due to the combined effect of morphological and compositional differences. The commendable catalytic efficiency along with the facile synthetic approach and the use of low-cost copper and nickel significantly reduces the cost of the catalytic process. The stability of the Cu-CuO-Ni catalyst system for the chromium reduction reactions was monitored by conducting recyclability test for three times. Therefore, the developed Cu-CuO-Ni nanocatalyst offers significant applications in waste water treatment systems and other industrial applications.

Harez Rashid Ahmed, Fryad S. Mustafa, Kosar Hikmat Hama Aziz, Steven John Hinder (2023)Utilizing sequence transformation of selective copper metal as an efficient heterogeneous Fenton-like catalyst for the degradation of aqueous methylene blue, In: Reaction kinetics, mechanisms and catalysis
Bowei Li, Yuren Xiang, K.D.G. Imalka Jayawardena, Deying Luo, Zhuo Wang, Xiaoyu Yang, John F. Watts, Steven Hinder, Muhammad T. Sajjad, Thomas Webb, Haitian Luo, Igor Marko, Hui Li, Stuart A.J. Thomson, Rui Zhu, Guosheng Shao, Stephen J. Sweeney, S. Ravi P. Silva, Wei Zhang (2020)Reduced bilateral recombination by functional molecular interface engineering for efficient inverted perovskite solar cells, In: Nano Energy105249 Elsevier

Interface-mediated recombination losses between perovskite and charge transport layers are one of the main reasons that limit the device performance, in particular for the open-circuit voltage (VOC) of perovskite solar cells (PSCs). Here, functional molecular interface engineering (FMIE) is employed to retard the interfacial recombination losses. The FMIE is a facile solution-processed means that introducing functional molecules, the fluorene-based conjugated polyelectrolyte (CPE) and organic halide salt (OHS) on both contacts of the perovskite absorber layer. Through the FMIE, the champion PSCs with an inverted planar heterojunction structure show a remarkable high VOC of 1.18 V whilst maintaining a fill factor (FF) of 0.83, both of which result in improved power conversion efficiencies (PCEs) of 21.33% (with stabilized PCEs of 21.01%). In addition to achieving one of the highest PCEs in the inverted PSCs, the results also highlight the synergistic effect of these two molecules in improving device performance. Therefore, the study provides a straightforward avenue to fabricate highly efficient inverted PSCs.

Amvrosios G. Georgiadis, Georgios I. Siakavelas, Anastasios I. Tsiotsias, Nikolaos D. Charisiou, Benedikt Ehrhardt, Wen Wang, Victor Sebastian, Steven J. Hinder, Mark A. Baker, Simone Mascotto, Maria A. Goula (2023)Biogas dry reforming over Ni/LnOx-type catalysts (Ln = La, Ce, Sm or Pr), In: International journal of hydrogen energy48(52)pp. 19953-19971 Elsevier Ltd

Ni/LnOx-type catalysts (Ln = La, Ce, Sm or Pr, denoted as LNO, CNO, SNO and PNO, respectively) were prepared via a citrate sol-gel method, characterized, and evaluated for the dry reforming of biogas. For the calcined catalysts, the formation of LaNiO3 perovskite crystallites with high purity was observed in the case of La, whereas NiO-LnOx mixed oxides were obtained for the other lanthanides. The reduction treatment led to the formation of medium-sized (∼15 nm) and highly dispersed Ni nanoparticles in LNO following the decomposition of the LaNiO3 perovskite, in contrast to the other catalysts, where bigger Ni crystallites were formed (∼30 nm). As a result, LNO was shown to possess a higher catalytic activity in comparison to the other materials. Regarding the catalytic stability, LNO displayed a considerable activity loss followed by a high pressure drop due to reactor blockage, meaning that the use of Sm (Ni/Sm2O3) can be considered as an alternative strategy to restrict catalyst deactivation. As evidenced by the characterization of the spent catalysts, the deactivation for the most part can be attributed to the extensive coke deposition over the catalysts. The coke deposited was found to be both in the form of more disordered/amorphous carbon, as well as in the form of highly crystalline and multi-walled carbon nanotubes. •Ni/LnOx catalysts (Ln = La, Ce, Sm or Pr) were tested for biogas dry reforming.•LaNiO3 was formed for La and segregated NiO-LnOx for the other lanthanides.•Decomposition of LaNiO3 perovskite led to smaller Ni nanoparticles.•LNO presented improved activity but high activation energy and reduced stability.•Deactivation observed due to amorphous and crystalline coke formation.

N.D. Charisiou, G. Siakavelas, L. Tzounis, B. Dou, V. Sebastian, S.J. Hinder, M.A. Baker, K. Polychronopoulou, M.A. Goula (2019)Ni/Y2O3–ZrO2 catalyst for hydrogen production through the glycerol steam reforming reaction, In: International Journal of Hydrogen Energy Elsevier

In the study presented herein, the catalytic activity and stability of a Ni catalyst supported on Y2O3–ZrO2 was examined for the first time in the glycerol steam reforming reaction and compared with a Ni/ZrO2. The addition of Y2O3 stabilized the ZrO2 tetragonal phase, increased the O2 storage capacity of the support and the medium strength acid sites of the catalyst, and although the Ni/Zr catalyst had a higher concentration of basic sites, the Ni/YZr presented more stable monodentate carbonates. Moreover, the Ni/YZr had substantially higher Ni surface concentration and smaller Ni particles. These properties influence the gaseous products’ distribution by increasing the H2 yield and selectivity and preventing the transformation of CO2 to CO, by inhibiting the reverse water gas shift (RWGS) reaction from taking place. For both catalysts the main liquid products identified were allyl alcohol, acetaldehyde, acetone, acrolein, acetic acid and acetol; these were subsequently quantified. The time-on-stream experiments showed that the Ni/YZr was more stable during reaction and had a higher H2 yield after 20 h (2.17 in comparison to 1.50 mol H2/mol C3H8O3, for the Ni/Zr). Extensive investigation of the carbon deposits showed that although lower amounts of coke were deposited on the Ni/Zr catalyst, these structures were more graphitic in nature and had fewer defects, which means they were harder to oxidize. Moreover, transmission electron microscopy (TEM) analysis showed that sintering of Ni nanoparticles during the reaction was significant for the Ni/Zr catalyst, as the mean particle diameter increased from an initial value of 48.2 to 67.9 nm, while it was almost absent on the Ni/YZr catalyst (the mean particle diameter increased from 42.1 to 47.4 nm).

Harez R. Ahmed, Kosar Hikmat Hama Aziz, Nian N. M. Agha, Fryad S. Mustafa, Steven John Hinder (2023)Iron-loaded carbon black prepared via chemical vapor deposition as an efficient peroxydisulfate activator for the removal of rhodamine B from water, In: RSC advances13(37)pp. 26252-26266 The Royal Society of Chemistry

The excessive use of organic pollutants like organic dyes, which enter the water environment, has led to a significant environmental problem. Finding an efficient method to degrade these pollutants is urgent due to their detrimental effects on aquatic organisms and human health. Carbon-based catalysts are emerging as highly promising and efficient alternatives to metal catalysts in Fenton-like systems. They serve as persulfate activators, effectively eliminating recalcitrant organic pollutants from wastewater. In this study, iron-loaded carbon black (Fe-CB) was synthesized from tire waste using chemical vapor deposition (CVD). Fe-CB exhibited high efficiency as an activator of peroxydisulfate (PDS), facilitating the effective degradation and mineralization of rhodamine B (RhB) in water. A batch experiment and series characterization were conducted to study the morphology, composition, stability, and catalytic activity of Fe-CB in a Fenton-like system. The results showed that, at circumneutral pH, the degradation and mineralization efficiency of 20 mg L −1 RhB reached 92% and 48% respectively within 60 minutes. Fe-CB exhibited excellent reusability and low metal leaching over five cycles while maintaining almost the same efficiency. The degradation kinetics of RhB was found to follow a pseudo-first-order model. Scavenging tests revealed that the dominant role was played by sulfate (SO 4 − ˙) and superoxide (O 2 − ˙) radicals, whereas hydroxyl radicals (OH˙) and singlet oxygen ( 1 O 2 ) played a minor role in the degradation process. This study elucidates the detailed mechanism of PDS activation by Fe-CB, resulting in the generation of reactive oxygen species. It highlights the effectiveness of Fe-CB/PDS in a Fenton-like system for the treatment of water polluted with organic dye contaminants. The research provides valuable insights into the potential application of carbon black derived from tire waste for environmental remediation. Fe-CB was synthesized via CVD from tire wastes and used for the degradation and mineralization of RhB by persulfate based advanced oxidation processes.

Sean Grabe, Joseph Paul Baboo, Stephen Tennison, Teng Zhang, Eleftherios I Andritsos, Qiong Cai, Stephen Downes, Stephen Hinder, John F. Watts, Constantina Lekakou (2022)Sulfur infiltration and allotrope formation in porous cathode hosts for lithium-sulfur batteries, In: AIChE journal68(7)e17638 Wiley

We investigate sulfur infiltration and formation of lower order allotropes in heated porous hosts during fabrication of lithium-sulfur (Li-S) battery cathodes. Sulfur existence in cathode ultramicropores has been an important question for Li-S batteries, as ultramicropores reduce the polysulfides " shuttle effect " but also delay sulfur dissolution and Li + ion diffusion in the trapped solid sulfur. A novel continuum-level model is presented including heat transfer and sulfur infiltration, either from the top of a porous host or from the porous host particle surface, and taking into account the pore size distribution. A novel decay factor in modeling sulfur infiltration incorporates the pore wall repulsion energy and allotrope formation energy (predicted by density functional theory [DFT] simulations). Simulations are performed for a microporous carbon fabric host and an activated carbon powder host with bimodal micropore and macropore size distribution , with Raman and X-ray photoemission spectroscopy (XPS) spectroscopy confirming the predicted existence of linear S 6 and S 4 in ultramicropores. K E Y W O R D S lithium-sulfur batteries, melt and vapor infiltration, pore size distribution in cathode, sulfur allotropes 1 | INTRODUCTION Lithium-sulfur (Li-S) batteries have been in the research focus in the last decade because of their high theoretical energy density, 2510 Wh kg À1 , abundance and low toxicity of sulfur. 1 Intensive effort has been devoted on the cathode, where sulfur is incorporated in a porous conductive host with the aim for the host to not only enhance electronic conductivity but also allow for cathode expansion on the insertion of Li + ions and formation of polysulfides Li 2 S x during discharge. 2 Additionally, effective cathode hosts offer means to trap the sulfur and polysulfides to limit polysulfide shuttling between cathode and anode, which would cause reduction in capacity and coulombic efficiency. 3,4 Suitable microstructural architectures, including small pores, pores with necks and hollow particles, 5,6 and hosts functionalized with chemical groups with high adsorption energy to sulfur and sulfides 7 can provide such good traps. Additional specifications for host porosity and pore size distribution (PSD) target a sulfur mass greater than 5 mg cm À2 , making up at least 70% of the cathode weight, to realize the high theoretical energy density of Li-S batteries. 8 There is a vast range of porous host material candidates for Li-S battery cathodes: porous carbons, 5,6,9 activated carbon (AC) fabrics or fibers, 10,11 graphene and graphene oxide, 12–15 and

Anastasios I. Tsiotsias, Nikolaos D. Charisiou, Ayesha AlKhoori, Safa Gaber, Victor Sebastian, Steven J. Hinder, Mark A. Baker, Kyriaki Polychronopoulou, Maria A. Goula (2022)Towards maximizing conversion of ethane and carbon dioxide into synthesis gas using highly stable Ni-perovskite catalysts, In: Journal of CO2 utilization61 Elsevier Ltd

Dry ethane reforming (DER) aims to utilize captured CO2 and ethane, which is found in large quantities in shale gas, towards the production of high-value synthesis gas. During the dry reforming of hydrocarbons, the interaction between the active metal and the underlying support, along with the choice of the operating temperature, are considered to be the main factors influencing a catalyst’s stability and coking resistance. In this work, the DER catalytic performance and stability of Ni-doped perovskite systems is compared with that of a typical impregnated Ni/Al2O3 catalyst. The calcined, reduced and spent catalysts are assessed using the ICP, XRD, N2 physisorption, H2-TPR, CO2-TPD, TEM, HAADF-STEM, EDS Mapping, XPS and TPO techniques. Ni-CaZrO3 (CZNO) consisting of partly exsolved Ni nanoparticles with a strong metal-support interaction is shown to be particularly stable and accumulate only a fraction of the coke that is deposited on the impregnated Ni/Al2O3 catalyst, which suffers from severe and rapid degradation under the reactant stream. By increasing the operating temperature to 750 °C, Ni-CaZrO3 can achieve almost total conversion of ethane and around 90% conversion of carbon dioxide towards synthesis gas, with no apparent loss of catalytic activity. [Display omitted] •Ni-CaZrO3 and Ni-SrZrO3 catalysts were tested for the dry reforming of ethane.•Ni-perovskite catalysts exhibit superior stability compared to impregnated Ni/Al2O3.•Ni/Al2O3 accumulates the most carbon on its surface.•Coke deposition is the best descriptor of catalytic activity loss at 600 °C.•Increasing the reaction temperature promotes catalytic activity and stability.

Ayesha A. AlKhoori, Kyriaki Polychronopoulou, Abderrezak Belabbes, Maguy Abi Jaoude, Lourdes F. Vega, Victor Sebastian, Steven Hinder, Mark A. Baker, Abdallah F. Zedan (2020)Cu, Sm co-doping effect on the CO oxidation activity of CeO2. A combined experimental and density functional study, In: Applied Surface Science521146305 Elsevier

The co-doping effect of a rare earth (RE) metal and a transition metal (TM) on ceria oxidation catalysis through the evaluation of samarium-copper co-doped catalysts with Ce-Sm-xCu-O (x: 0–20 at.%, Ce/Sm = 1) nominal compositions, is discussed. The CO oxidation reaction was used as a prototype reaction due to its pivotal role in the fuel cell technology. Ce-Sm-20Cu-O catalyst presented a 64% increase in the CO oxidation activity compared to that of pristine ceria. Diffraction and Raman studies proved that the Cu, Sm co-doping induces many defects related to the dopants (Sm, Cu) and the oxygen vacant sites, while the presence of hybrid CuO/Ce-Sm(Cu)-O fluorite/SmO8 (cubic metastable) phases is the most representative scenario of this oxide microstructure. A size polydispersity of CuO phases was achieved by introducing air cooling during the microwave heating. Cu, Sm atoms were uniformly doped in CeO2 structure according to the HAADF-STEM studies. These results are in agreement with EDS analysis, where Cu, Sm and Ce are located in all the analyzed areas without any preferential distribution. The XPS studies demonstrated the co-presence of Cu2+/Cu1+ and Ce4+/Ce3+ redox couples in agreement with the Bader charge analysis from the ab initio calculations, the latter influencing greatly the oxidation activity of the catalysts. Density functional theory (DFT) calculations shed light on the oxide surface and the underlying mechanism governing the oxidation catalysis taking place. In particular, Cu2+ and Sm3+ dopants were found to be located in the nearest neighbor (NN) sites of oxygen vacancies. Different oxygen vacancies configurations were studied (single vs. double, surface vs. subsurface), where the single vacancies are more stable on the surface, whereas the double vacancies configurations are more stable on the subsurface. Regarding the Ce3+ location, in the presence of single and double oxygen vacancy, the Ce3+ ions prefer to be located in the 1st NN/2nd NN and 2nd NN of the first Ce layer, relative to the oxygen vacancy, respectively. The total Density of States (DOS) analysis of the co-doped systems revealed that the dopants induced new surface states inside the ceria band gap, which can accommodate the unpaired electrons of the vacant oxygen sites. These electronic modifications justify the much lower energy of oxygen vacancy formation (Evf) in both cases, the Sm-doped, and Cu, Sm -doped CeO2 (1 1 1) geometries. Specifically, the Evf lowering upon doping was found to be almost two times larger for the Cu adjacent oxygen vacancies (Cu2+-□) compared to the Sm ones (Sm3+-□), consistent with the CO adsorption trend as the Cu-Sm-CeO2 (1 1 1) system is energetically more favorable than the Sm-CeO2 (1 1 1) and pure CeO2 (1 1 1) surfaces.

Wenliang Feng, Venkata Sai Avvaru, Rudi Ruben Maça, Steven J Hinder, Miguel Castillo Rodríguez, Vinodkumar Etacheri (2021)Realization of High Energy Density Sodium-Ion Hybrid Capacitors through Interface Engineering of Pseudocapacitive 3D-CoO-NrGO Hybrid Anodes, In: ACS applied materials & interfaces13(24)pp. 27999-28009 American Chemical Society

Sodium-ion hybrid capacitors (SHCs) have attracted great attention owing to the improved power density and cycling stability in comparison with sodium-ion batteries. Nevertheless, the energy density (

Bowei Li, Yuren Xiang, Imalka Jayawardena, Deying Luo, John Watts, Steven Hinder, Hui Li, Victoria Ferguson, Haitian Luo, Rui Zhu, S. Ravi P. Silva, Wei Zhang (2020)Tailoring Perovskite Adjacent Interfaces by Conjugated Polyelectrolyte for Stable and Efficient Solar Cells, In: Solar RRL4(5)2000060 Wiley

Interface engineering is an effective means to enhance the performance of thin‐film devices, such as perovskite solar cells (PSCs). Herein, a conjugated polyelectrolyte, poly[(9,9‐bis(3′‐((N,N‐dimethyl)‐N‐ethyl‐ammonium)‐propyl)‐2,7‐fluorene)‐alt‐2,7‐(9,9‐dioctylfluorene)]di‐iodide (PFN‐I), is used at the interfaces between the hole transport layer (HTL)/perovskite and perovskite/electron transport layer simultaneously, to enhance the device power conversion efficiency (PCE) and stability. The fabricated PSCs with an inverted planar heterojunction structure show improved open‐circuit voltage (Voc), short‐circuit current density (Jsc), and fill factor, resulting in PCEs up to 20.56%. The devices maintain over 80% of their initial PCEs after 800 h of exposure to a relative humidity 35–55% at room temperature. All of these improvements are attributed to the functional PFN‐I layers as they provide favorable interface contact and defect reduction.

M. A. Baker, G. I. Siakavelas, N.D. Charisiou, A. AlKhoori, S. AlKhoori, V. Sebastian, S. J. Hinder, I.V. Yentekakis, K. Polychronopoulou, M.A. Goula (2021)Highly selective and stable Ni/La-M (M=Sm, Pr, and Mg)-CeO2 catalysts for CO2 methanation, In: Journal of CO₂ Utilization51101618 Elsevier

In the study presented herein, nickel catalysts supported on CeO2 and, for the first time in the literature, on La2O3-Sm2O3-CeO2, La2O3-Pr2O3-CeO2 and La2O3-MgO-CeO2 were prepared and evaluated for the reaction of CO2 methanation. The carriers were prepared through a sol-gel microwave assisted method and the catalysts were obtained following wet impregnation. The physicochemical properties of the catalysts prior to reaction were determined through H2-TPR, H2-TPD, Raman spectroscopy, XRD, CO2-TPD, N2 physisorption-desorption, XPS and TEM. The spent catalysts, after the time-on-stream experiments were further characterised using TEM and TGA. It was shown that the simultaneous incorporation of La3+, Pr3+ and La3+, Sm3+ into the crystal structure of cerium oxide created higher population of oxygen vacant sites. Moreover, the co-presence of La3+, Mg2+ and La3+, Pr3+ into the CeO2 increased the plethos of moderate basic sites. These physicochemical properties increased the rate of CO2 methanation reaction at relatively low temperatures. Furthermore, it is argued that the addition of La3+ stabilized the Ni active sites via the probable formation of a new compound (La-O-Ni) on the catalyst surface or synergetic catalytic centers at the interfacial area improving the catalytic properties (activity and stability). Finally, the catalytic performance tests revealed that the addition of La3+ mainly improved the conversion of CO2 and yield of CH4 for the Ni/La-Mg-Ce and Ni/La-Sm-Ce samples. The rCO2 and XCO2 values at 300oC followed the order Ni/La-Sm-Ce >> Ni/La-Mg-Ce > Ni/La-Pr-Ce > Ni/Ce.

Joseph Paul Baboo, Mudasir A. Yatoo, Matthew Dent, Elaheh Hojaji Najafabadi, Constantina Lekakou, Robert Slade, Steven J. Hinder, John F. Watts (2022)Exploring Different Binders for a LiFePO4 Battery, Battery Testing, Modeling and Simulations, In: Energies (Basel)15(7) Mdpi

This paper focuses on the LiFePO4 (LFP) battery, a classical and one of the safest Li-ion battery technologies. To facilitate and make the cathode manufacture more sustainable, two Kynar (R) binders (Arkema, France) are investigated which are soluble in solvents with lower boiling points than the usual solvent for the classical PVDF binder. Li-LFP and graphite-Li half cells and graphite-LFP full cells are fabricated and tested in electrochemical impedance spectroscopy, cyclic voltammetry (CV) and galvanostatic charge-discharge cycling. The diffusion coefficients are determined from the CV plots, employing the Rendles-Shevchik equation, for the LFP electrodes with the three investigated binders and the graphite anode, and used as input data in simulations based on the single-particle model. Microstructural and surface composition characterization is performed on the LFP cathodes, pre-cycling and after 25 cycles, revealing the aging effects of SEI formation, loss of active lithium, surface cracking and fragmentation. In simulations of battery cycling, the single particle model is compared with an equivalent circuit model, concluding that the latter is more accurate to predict "future" cycles and the lifetime of the LFP battery by easily adjusting some of the model parameters as a function of the number of cycles on the basis of historical data of cell cycling.

Priyanka Ganguly, Syam Kumar R., Marica Muscetta, Nisha T. Padmanabhan, Laura Clarizia, A. Akande, Steven Hinder, Snehamol Mathew, Honey John, Ailish Breen, Suresh C. Pillai (2021)New insights into the efficient charge transfer of ternary chalcogenides composites of TiO2, In: Applied catalysis. B, Environmental282 Elsevier B.V

[Display omitted] •Preparation of novel heterostructures of AgBiSe2-TiO2 and AgInSe2-TiO2.•Computational study of AgBiSe2, AgInSe2 and TiO2.•p-n heterojunction constructed in AgBiSe2-TiO2•Type II heterojunction observed for AgInSe2-TiO2 composites.•Delayed recombination and well-matched band gaps result in charge separation. A two-step solvothermal synthesis was adopted to prepare AgXSe2-TiO2 (X = In, Bi) composites. DFT study of the pristine parent samples showed the formation of the hexagonal phase of AgBiSe2, and tetragonal phase of AgInSe2 and TiO2, which corroborated the experimentally synthesised structures. Both the AgBiSe2-TiO2 and AgInSe2-TiO2 composites displayed enhanced visible light absorption and reduced band gap in the UV-DRS patterns. The XPS results exhibited a shift in binding energy values and the TEM results showed the formation of spherical nanoparticles of both AgBiSe2 and AgInSe2. The PL signals displayed delayed recombination of the photogenerated excitons. The as synthesised materials were studied for their photocatalytic efficiency, by hydrogen generation, degradation of doxycycline, and antimicrobial disinfection (E. coli and S. aureus). The composite samples illustrated more than 95 % degradation results within 180 min and showed 5 log reductions of bacterial strains within 30 min of light irradiation. The hydrogen production outcomes were significantly improved as the AgBiSe2 and AgInSe2 based composites illustrated 180-fold and 250-fold enhanced output compared to their parent samples. The enhanced photocatalytic efficiency displayed is attributed to the delayed charge recombination of the photogenerated electron-hole pairs in the AgXSe2-TiO2 interface. Formation of a p-n nano heterojunction for AgBiSe2-TiO2 and type II heterojunction for AgInSe2-TiO2 composite are explained.

Venkata Sai Avvaru, Mewin Vincent, Ivan Jimenez Fernandez, Steven J. Hinder, Vinodkumar Etacheri (2022)Unusual pseudocapacitive lithium-ion storage on defective Co3O4nanosheets, In: Nanotechnology33(22) IOP Publishing Ltd

Secondary lithium-ion batteries are restricted in large-scale applications including power grids and long driving electric vehicles owing to the low specific capacity of conventional intercalation anodes possessing sluggish Li-ion diffusion kinetics. Herein, we demonstrate an unusual pseudocapacitive lithium-ion storage on defective Co3O4 nanosheet anodes for high-performance rechargeable batteries. Cobalt-oxide nanosheets presented here composed of various defects including vacancies, dislocations and grain boundaries. Unique 2D holey microstructure enabled efficient charge transport as well as provided room for volume expansions associated with lithiation-delithiation process. These defective anodes exhibited outstanding pseudocapacitance (up to 87%), reversible capacities (1490 mAh g(-1) @ 25 mA g(-1)), rate capability (592 mAh g(-1) @ 30 A g(-1)), stable cycling (85% after 500 cycles @ 1 A g(-1)) and columbic efficiency (similar to 100%). Exceptional Li-ion storage phenomena in defective Co3O4 nanosheets is accredited to the pseudocapacitive nature of conversion reaction resulting from ultrafast Li-ion diffusion through various crystal defects. The demonstrated approach of defect-induced pseudocapacitance can also be protracted for various low-cost and/or eco-friendly transition metal-oxides for next-generation rechargeable batteries.

Kyriakos N. Papageridis, Nikolaos D. Charisiou, Savvas Douvartzides, Victor Sebastian, Steven J. Hinder, Mark A. Baker, Sara AlKhoori, Kyriaki Polychronopoulou, Maria A. Goula (2020)Promoting effect of CaO-MgO mixed oxide on Ni/γ-Al2O3 catalyst for selective catalytic deoxygenation of palm oil, In: Renewable energy162pp. 1793-1810 Elsevier Ltd

The study presented herein examines, for the first time in the literature, the role of CaO-MgO as a modifier of γ-Αl2O3 for Ni catalysts for the production of green diesel through the deoxygenation of palm oil. The characteristics of the catalytic samples were examined by N2 adsorption/desorption, XRD, NH3-TPD, CO2-TPD, H2-TPR, XPS and TEM analysis. The carbon deposited on the catalytic surfaces was characterized by TPO, Raman and TEM/HR-TEM. Experiments were conducted between 300 and 400 °C, at 30 bar. Maximum triglyceride conversion and the yield of the target n–C15–n–C18 paraffins increased with temperature up to 375 °C for both catalysts. Both samples promoted deCO2 and deCO deoxygenation reactions much more extensively than HDO. However, although both catalysts exhibited similar activity at the optimal temperature of 375 °C, the Ni/modAl was more active at lower reaction temperatures, which can be probably understood on the basis of the increased dispersion of Ni on its surface and its lower acidity, which suppressed hydrocracking reactions. Time-on-stream experiments carried out for 20 h showed that the Ni/modAl catalyst was considerably more stable than the Ni/Al, which was attributed to the lower amount and lower crystallinity of the carbon deposits and to the suppression of sintering due to the presence of the CaO-MgO modifiers. •Ni on CaO-MgO-Al2O3 highly selective and stable for green diesel production.•Presence of CaO and MgO leads to significantly increased amount of Ni0 active phase.•Presence of CaO and MgO prevents Ni sintering during reaction.•Presence of CaO and MgO leads to the formation of less graphitic carbon structures.

Nikolaos Kostoglou, Chi-Wei Liao, Cheng-Yu Wang, Junko N. Kondo, Christos Tampaxis, Theodore Steriotis, Konstantinos Giannakopoulos, Athanassios G. Kontos, Steven Hinder, Mark Baker, Etienne Bousser, Allan Matthews, Claus Rebholz, Christian Mitterer (2021)Effect of Pt nanoparticle decoration on the H2 storage performance of plasma-derived nanoporous graphene, In: CARBON171pp. 294-305 PERGAMON-ELSEVIER SCIENCE LTD

A nanoporous and large surface area (∼800 m2/g) graphene-based material was produced by plasma treatment of natural flake graphite and was subsequently surface decorated with platinum (Pt) nano-sized particles via thermal reduction of a Pt precursor (chloroplatinic acid). The carbon-metal nanocomposite showed a ∼2 wt% loading of well-dispersed Pt nanoparticles (

Kyriakos N Papageridis, Nikolaos D Charisiou, Savvas Douvartzides, Victor Sebastian, Steven J Hinder, Mark A Baker, Ayesha A AlKhoori, Sara I AlKhoori, Kyriaki Polychronopoulou, Maria A Goula (2021)Continuous selective deoxygenation of palm oil for renewable diesel production over Ni catalysts supported on Al2O3and La2O3-Al2O3, In: RSC advances11(15)pp. 8569-8584 Royal Society of Chemistry

The present study provides, for the first time in the literature, a comparative assessment of the catalytic performance of Ni catalysts supported on γ-Al2O3 and γ-Al2O3 modified with La2O3, in a continuous flow trickle bed reactor, for the selective deoxygenation of palm oil. The catalysts were prepared via the wet impregnation method and were characterized, after calcination and/or reduction, by N2 adsorption/desorption, XRD, NH3-TPD, CO2-TPD, H2-TPR, H2-TPD, XPS and TEM, and after the time-on-stream tests, by TGA, TPO, Raman and TEM. Catalytic experiments were performed between 300–400 °C, at a constant pressure (30 bar) and different LHSV (1.2–3.6 h−1). The results show that the incorporation of La2O3 in the Al2O3 support increased the Ni surface atomic concentration (XPS), affected the nature and abundance of surface basicity (CO2-TPD), and despite leading to a drop in surface acidity (NH3-TPD), the Ni/LaAl catalyst presented a larger population of medium-strength acid sites. These characteristics helped promote the SDO process and prevented extended cracking and the formation of coke. Thus, higher triglyceride conversions and n-C15 to n-C18 hydrocarbon yields were achieved with the Ni/LaAl at lower reaction temperatures. Moreover, the Ni/LaAl catalyst was considerably more stable during 20 h of time-on-stream. Examination of the spent catalysts revealed that both carbon deposition and degree of graphitization of the surface coke, as well as, the extent of sintering were lower on the Ni/LaAl catalyst, explaining its excellent performance during time-on-stream.

Anastasios I. Tsiotsias, Sanaa Hafeez, Nikolaos D. Charisiou, Sultan M. Al-Salem, George Manos, Achilleas Constantinou, Sara AlKhoori, Victor Sebastian, Steven J. Hinder, Mark A. Baker, Kyriaki Polychronopoulou, Maria A. Goula (2023)Selective catalytic deoxygenation of palm oil to produce green diesel over Ni catalysts supported on ZrO2 and CeO2–ZrO2: Experimental and process simulation modelling studies, In: Renewable energy206pp. 582-596 Elsevier Ltd

The selective deoxygenation of palm oil to produce green diesel has been investigated over Ni catalysts supported on ZrO2 (Ni/Zr) and CeO2–ZrO2 (Ni/CeZr) supports. The modification of the support with CeO2 acted to improve the Ni dispersion and oxygen lability of the catalyst, while reducing the overall surface acidity. The Ni/CeZr catalyst exhibited higher triglyceride (TG) conversion and yield for the desirable C15–C18 hydrocarbons, as well as improved stability compared to the unmodified Ni/Zr catalyst, with TG conversion and C15–C18 yield remaining above 85% and 80% respectively during 20 h of continuous operation at 300 oC. The high C17 yields also revealed the dominance of the deCOx (decarbonylation/decarboxylation) pathway. A fully comprehensive process simulation model has been developed to validate the experimental findings in this study, and a very good validation with the experimental data has been demonstrated. The model was then further utilised to investigate the effects of temperature, H2 partial pressure, H2/oil feed ratio and LHSV. The model predicted that maximum triglyceride conversion was attainable at reaction conditions of 300 °C temperature, 30 bar H2 partial pressure, H2/oil of 1000 cm3/cm3 feed ratio and 1.2 h−1 LHSV. [Display omitted]

Bowei Li, Jun Deng, Joel A. Smith, Pietro Caprioglio, Kangyu Ji, Deying Luo, James D. McGettrick, K. D. G. Imalka Jayawardena, Rachel Kilbride, AOBO REN, Stephen Sweeney, Steven John Hinder, Jinxin Bi, S Ravi Pradip Silva, Wei Zhang, THOMAS WEBB, Igor Marko, Xueping Liu, YUREN XIANG, Joshua Dean Reding, HUI LI, Shixuan Du, D. G. Lidzey, Samuel D. Stranks, Trystan M. Watson, H. J. Snaith (2022)Suppressing Interfacial Recombination with a Strong-Interaction Surface Modulator for Efficient Inverted Perovskite Solar Cells, In: Advanced energy materials Wiley

Successful manipulation of halide perovskite surfaces is typically achieved via the interactions between modulators and perovskites. Herein, it is demonstrated that a strong-interaction surface modulator is beneficial to reduce interfacial recombination losses in inverted (p-i-n) perovskite solar cells (IPSCs). Two organic ammonium salts are investigated, consisting of 4-hydroxyphenethylammonium iodide and 2-thiopheneethylammonium iodide (2-TEAI). Without thermal annealing, these two modulators can recover the photoluminescence quantum yield of the neat perovskite film in contact with fullerene electron transport layer (ETL). Compared to the hydroxyl-functionalized phenethylammonium moiety, the thienylammonium facilitates the formation of a quasi-2D structure onto the perovskite. Density functional theory and quasi-Fermi level splitting calculations reveal that the 2-TEAI has a stronger interaction with the perovskite surface, contributing to more suppressed non-radiative recombination at the perovskite/ETL interface and improved open-circuit voltage (V-OC) of the fabricated IPSCs. As a result, the V-OC increases from 1.11 to 1.20 V (based on a perovskite bandgap of 1.63 eV), yielding a power conversion efficiency (PCE) from approximate to 20% to 21.9% (stabilized PCE of 21.3%, the highest reported PCEs for IPSCs employing poly[N,N ''-bis(4-butylphenyl)-N,N ''-bis(phenyl)benzidine] as the hole transport layer, alongside the enhanced operational and shelf-life stability for unencapsulated devices.

W. Hashini K. Perera, Mateus G. Masteghin, Hongjae Shim, Joshua L. Ryan, Steven J. Hinder, Jae S. Yun, Wei Zhang, K. D. G. Imalka Jayawardena, S Ravi Pradip Silva (2023)Modification of Hydrophobic Self-Assembled Monolayers with Nanoparticles for Improved Wettability and Enhanced Carrier Lifetimes Over Large Areas in Perovskite Solar Cells, In: Solar RRL Wiley

The development of perovskite solar cells (PSCs) with low recombination losses, at low processing temperatures is an area of growing research interest as it enables compatibility with roll-to-roll processing on flexible substrates as well as with tandem solar cells. The inverted or p-i-n device architecture has emerged as the most promising PSC configuration due to the possibility of using low temperature processable organic hole transport layers and more recently, self-assembled monolayers such as, [4-(3,6-Dimethyl-9H-carbazol-9-yl)butyl]phosphonic Acid (Me-4PACz). However, devices incorporating these interlayers suffer from poor wettability of the precursor leading to pin hole formation and poor device yield. Here, we demonstrate the use of alumina nanoparticles (Al2O3 NPs) for pinning the perovskite precursor on Me-4PACz, thereby improving the device yield. While similar wettability enhancements can also be achieved by using poly[(9,9-bis(3’-((N,N-dimethyl)-N-ethylammonium)-propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)]dibromide (PFN-Br), a widely employed surface modifier, the incorporation of Al2O3 NPs results in significantly enhanced Shockley-Read-Hall recombination lifetimes exceeding 3 μs, which is higher than those on films coated directly on Me-4PACz and on PFN-Br modified Me-4PACz. This translates to a champion power conversion efficiency of 19.9% for PSCs fabricated on Me-4PACz modified with Al2O3, which is a ∽20% improvement compared to the champion device fabricated on PFN-Br modified Me-4PACz.

K.N Papageridis, N.D Charisiou, S.L Douvartzides, V. Sebastian, S.J Hinder, M.A Baker, S. AlKhoori, K. Polychronopoulou, M.A Goula (2020)Effect of operating parameters on the selective catalytic deoxygenation of palm oil to produce renewable diesel over Ni supported on Al2O3, ZrO2 and SiO2 catalysts, In: Fuel Processing Technology Elsevier

The present work investigated the production of Green Diesel through the deoxygenation of palm oil over Ni catalysts supported on γ-Αl2O3, ZrO2 and SiO2 for a continuous flow fixed bed reactor. A comprehensive experimental study was carried out in order to examine the effects of temperature, pressure, LHSV and H2/oil feed ratio on catalytic activity during short (6 h) and long (20 h) time-on-stream experiments. The catalysts were prepared through the wet impregnation method (8 wt.% Ni) and were extensively characterized by N2 adsorption/desorption, XRD, NH3-TPD, CO2-TPD, H2-TPD, H2-TPR, XPS, TEM/HR-TEM and Raman. The characterization of the materials prior to reaction revealed that although relatively small Ni nanoparticles were achieved for all catalysts (4.3 ± 1.6 nm, 6.1 ± 1.8 nm and 6.0 ± 1.8 nm for the Ni/Al2O3, Ni/ZrO2 and Ni/SiO2 catalysts, respectively), NiO was better dispersed on the Ni/ZrO2 catalyst, while the opposite was true for the Ni/SiO2 sample. In the case of Ni/Al2O3, part of Ni could not participate in the reaction due to its entrapment in the NiAl2O4 spinel phase. Regarding performance, although an increase in H2 pressure led to increases in paraffin conversion, the increase of temperature was beneficial only up to a critical value which differed for each catalytic system under consideration (375 oC, 300 oC and 350 oC for the Ni/Al2O3, Ni/ZrO2 and Ni/SiO2 catalysts, respectively). All catalysts favored the deCO2 and deCO deoxygenation paths much more extensively than HDO, irrespective of testing conditions. Time-on-stream experiments showed that all catalysts deactivated after about 6 h, which was attributed to the sintering of the Ni particles and/or their covering by a thin graphitic carbon shell.

Venkata Sai Avvaru, Ivan Jimenez Fernandez, Wenliang Feng, Steven J. Hinder, Miguel Castillo Rodríguez, Vinodkumar Etacheri (2021)Extremely pseudocapacitive interface engineered CoO@3D-NRGO hybrid anodes for high energy/ power density and ultralong life lithium-ion batteries, In: Carbon (New York)171pp. 869-881 Elsevier Ltd

Although secondary Li-ion batteries are widely used for electrochemical energy storage, low energy (100–300 Wh kg−1) and power density (250–400 W kg−1) are limiting their applications in several areas including long-range electric vehicles. Herein, we demonstrate high energy (400 Wh kg−1) and power density (1 kW kg−1) Li-ion batteries (considering the weight of both electrodes) based on extremely pseudocapacitive interface engineered CoO@3D-NRGO hybrid anodes. These values are 2.8 and 2.3-fold higher respectively compared to graphite‖LiNiMnCoO2 full-cells under similar experimental conditions. Three-dimensional anode architecture presented here composed of ultrafine CoO nanoparticles (∼10 nm) chemically bonded to nitrogen-doped reduced graphene-oxide. This hybrid anode demonstrated excellent pseudocapacitance (∼92%), specific capacity (1429 mAh g−1 @ 25 mA g−1), rate performance (906 mAh g−1 @ 5 A g−1), and cycling stability (990 mAh g−1 after 7500 cycles @ 5 A g−1). Outstanding electrochemical performance of CoO@3D-NRGO‖LiNiMnCoO2 full-cells is credited to the extreme pseudocapacitance of CoO@3D-NRGO anode resulting from Li2O/Co/NRGO nanointerfaces and Co–O–C bonds. The demonstrated strategy of interfacial engineering can also be extended for other environmental friendly/inexpensive transition metal oxide (Fe2O3, MnO2 etc.) anodes for high energy/power density and ultra-long-life Li-ion batteries. [Display omitted] •Extremely pseudocapacitive CoO@3D-NRGO hybrid Li-ion battery anodes are developed.•Li-ion battery exhibited high energy (400 Wh kg−1) and power density (1 kW kg−1).•These values are 2.8 and 2.3-fold higher compared to graphite anode based system.•Li2O/Co/NRGO nanointerfaces and Co–O–C bonds caused extreme pseudocapacitance.•This strategy provides new opportunities to design advanced Li-ion batteries.

Aasif A. Dabbawala, Omer Elmutasim, Mark A. Baker, Georgios Siakavelas, Dalaver H. Anjum, Nikolaos D. Charisiou, Steven J. Hinder, Catherine J. Munro, Marko Gacesa, Maria A. Goula, Kyriaki Polychronopoulou (2023)Toward maximizing the selectivity of diesel-like hydrocarbons from oleic acid hydrodeoxygenation using Ni/Co-Al2O3embedded mesoporous silica nanocomposite catalysts: An Experimental and DFT Approach, In: Applied surface science158294
Vattakkoval Nisha, Sreejesh Moolayadukkam, Anjali Paravannoor, Deepthi Panoth, Yu-Hsu Chang, Shajesh Palantavida, Steven J. Hinder, Suresh C. Pillai, Baiju Kizhakkekilikoodayil Vijayan (2022)Cu doped graphitic C3N4 for p-nitrophenol reduction and sensing applications, In: Inorganic chemistry communications142 Elsevier B.V

[Display omitted] •A series of Cu doped g-C3N4 catalysts were synthesized.•The samples used for catalytic hydrogenation of p-nitrophenol (Para-NP).•The sensor performance of prepared samples towards paracetamol was investigated.•g-C3N4 with 1% Cu exhibits superior catalytic performance and sensor activity. A series of Cu doped graphitic carbon nitride (g-C3N4) catalysts with different ratios of copper were synthesized by thermal method, using urea and copper sulphate as precursors. XPS (X-ray Photoelectron Spectroscopy) studies indicated that the peak of N1s at 398.9 eV is due to CuN bond and a peak at 932.9 eV showed the presence of CuNC bond. Catalytic hydrogenation of p-nitrophenol (Para-NP) to para-aminophenol (Para-AP) in presence of g-C3N4 (gCN) and copper doped g-C3N4 (CN-Cu) with sodium borohydride (NaBH4) was investigated by UV–Visible spectroscopy. The as-synthesized graphitic carbon nitride with 1% copper (CN-1Cu) doped sample exhibits superior catalytic performance and higher stability compared to fine Cu powder in the second cycle. Additionally, electrochemical paracetamol sensing properties of the samples were studied using cyclic voltammetry and chronoamperometry. Consistent with the catalytic performances, CN-1Cu exhibited greater sensitivity towards the detection of paracetamol within the broad range of 38 µM to 3.64 mM and the study was carried out in the physiological pH ∼ 7.4.

AG Kochur, TM Ivanova, SJ Hinder, JF Watts, AA Sidorov, MA Kiskin, VM Novotortsev, IL Eremenko (2011)X-ray photoelectron spectroscopy study of electron and spatial structure of mono- and binuclear Ni(II) carboxylate complexes with nitrogen-containing ligands, In: Journal of Electron Spectroscopy and Related Phenomena184(8-10)pp. 501-507

Ni3s, Ni3p and Ni2p x-ray photoelectron spectra of mono-and binuclear carboxylate complexes of nickel with various geometry of metal ions environment are obtained. The spectra are calculated in an isolated ion approximation. The dependence of the spectral profiles and the structure of the charge-transfer satellites on the structure of the immediate environment of nickel atoms is established. The data obtained support the results of X-ray diffraction and magnetic studies.

SJ Hinder, C Lowe, JF Watts (2007)ToF-SIMS depth profiling of a complex polymeric coating employing a C-60 sputter source, In: SURFACE AND INTERFACE ANALYSIS39(6)pp. 467-475 JOHN WILEY & SONS LTD
Peter Jenkins, Liu Yang, James Thomason, Xinyong Chen, John F Watts, Steven J Hinder (2019)Investigation of Chemical and Physical Surface Changes of Thermally Conditioned Glass Fibres, In: Fibers7(1) MDPI

A number of analytical techniques were applied to investigate changes to the surface of unsized boron-free E-glass fibres after thermal conditioning at temperatures up to 700 °C. Novel systematic studies were carried out to investigate the fundamental strength loss from thermal conditioning. Surface chemical changes studied using X-ray photoelectron spectroscopy (XPS) showed a consistent increase in the surface concentration of calcium with increasing conditioning temperature, although this did not correlate well with a loss of fibre strength. Scanning electron microscopy fractography confirmed the difficulty of analysing failure-inducing flaws on individual fibre fracture surfaces. Analysis by atomic force microscopy (AFM) did not reveal any likely surface cracks or flaws of significant dimensions to cause failure: the observation of cracks before fibre fracture may not be possible when using this technique. Fibre surface roughness increased over the whole range of the conditioning temperatures investigated. Although surface roughness did not correlate precisely with fibre strength, there was a clear inverse relationship at temperatures exceeding 400 °C. The interpretation of the surface topography that formed between 400–700 °C produced evidence that the initial stage of phase separation by spinodal decomposition may have occurred at the fibre surface.

Nikolaos D. Charisiou, Georgios I. Siakavelas, Binlin Dou, Victor Sebastian, Steven Hinder, Mark Baker, Kyriaki Polychronopoulou, Maria A. Goula (2019)Nickel Supported on AlCeO3 as a Highly Selective and Stable Catalyst for Hydrogen Production via the Glycerol Steam Reforming Reaction, In: Catalysts9(5)

In this study, a critical comparison between two low metal (Ni) loading catalysts is presented, namely Ni/Al2O3 and Ni/AlCeO3 for the glycerol steam reforming (GSR) reaction. The surface and bulk properties of the catalysts were evaluated using a plethora of techniques, such as N2 adsorption/desorption, ICP-AES, XRD, XPS, SEM/EDX, TEM, CO2-TPD, NH3-TPD, H2-TPR. Carbon deposited on the catalysts surfaces was probed using TPO, SEM and TEM. It is demonstrated that Ce-modification of Al2O3 induces an increase of the surface basicity and Ni dispersion. These features lead to a higher conversion of glycerol to gaseous products (60% to 80%), particularly H2 and CO2, enhancement of WGS reaction and a higher resistance to coke deposition. Allyl alcohol was found to be the main liquid product for the Ni/AlCeO3 catalyst, the production of which ceases over 700 oC. It is also highly significant that the Ni/AlCeO3 catalyst demonstrated stable values for H2 yield (2.9-2.3) and selectivity (89-81%), in addition to CO2 (75-67%) and CO (23-29%) selectivity during a (20h) long time-on-stream study. Following the reaction, SEM/EDX and TEM analysis showed heavy coke deposition over the Ni/Al2O3 catalyst, whereas for the Ni/AlCeO3 catalyst TPO studies showed the formation of more defective coke, the latter being more easily oxidized

SC Padmanabhan, SC Pillai, J Colreavy, S Balakrishnan, DE McCormack, TS Perova, Y Gun'ko, SJ Hinder, JM Kelly (2007)A simple sol-gel processing for the development of high-temperature stable photoactive anatase titania, In: CHEMISTRY OF MATERIALS19(18)pp. 4474-4481 AMER CHEMICAL SOC
SJ Hinder, MA Baker, M Audronis, V Bellido-Gonzalez, P MacK (2012)Surface characterisation of PET modified using a p-DC or HIPIMS reactive sputter pre-treatment, In: Surface and Interface Analysis44(8)pp. 1063-1067

Surface-sensitive techniques have been employed to characterise a model polymer substrate surface, poly(ethylene terephthalate) (PET), after a reactive sputter pre-treatment using magnetically enhanced Cu or Ti sputter targets in a mixed Ar-O glow discharge plasma. The plasmas are produced using either medium-frequency pulsed direct current (p-DC) or low-frequency high power impulse (HIPIMS) sources. X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS) and sessile drop water contact angles were employed to investigate changes in PET surface chemistry and properties following surface modification using different p-DC and HIPIMS process parameters. The XPS results indicate that the chemical composition of plasma-treated PET surfaces (p-DC or HIPIMS) depends strongly on the processing parameters employed such as sputter target material, magnetic array type and power supply technology. XPS results demonstrate that the sputter target material employed is of primary importance as it dictates the quantity of metal deposited/implanted into the PET surface. XPS results show that the use of a Cu target resulted in ∼ 31-35 at.% of Cu incorporated into the PET surface (as CuO), while the use of a Ti target resulted in only 1-4 at. % incorporation (as TiO ). The SIMS spectra and XPS depth profiles of Cu-treated PET indicate that the CuO has formed a discrete film at the surface, offering predominant or total coverage of the underlying PET. However, for Ti-treated PET, both PET and Ti SIMS peaks are observed, and the XPS C1s peak shape is characteristic of PET, indicating that Ti has not formed a discrete film, but instead TiO species have been incorporated, probably as an island-like distribution into the surface of the PET. The formation of CuO and TiO on the PET surface leads to a reduction in the contact angle compared to native PET. Hence, both p-DC and HIPIMS reactive plasma pre-treatments result in a more hydrophilic surface, promoting adhesion and offering a flexible means to introduce a wide range of surface chemistries and properties to polymeric surfaces. Copyright © 2012 John Wiley & Sons, Ltd. Copyright © 2012 John Wiley & Sons, Ltd.

Chunyang Zhang, Sanket Bhoyate, Chen Zhao, Pawan Kahol, Nikolaos Kostoglou, Christian Mitterer, Steven Hinder, Mark Baker, Georgios Constantinides, Kyriaki Polychronopoulou, Claus Rebholz, Ram Gupta (2019)Electrodeposited Nanostructured CoFe2O4 for Overall Water Splitting and Supercapacitor Applications, In: Catalysts9(2)

To contribute to solving global energy problems, a multifunctional CoFe2O4 spinel was synthesized and used as a catalyst for overall water splitting and as an electrode material for supercapacitors. The ultra-fast one-step electrodeposition of CoFe2O4 over conducting substrates provides an economic pathway to high-performance energy devices. Electrodeposited CoFe2O4 on Ni-foam showed a low overpotential of 270 mV and a Tafel slope of 31 mV/dec. The results indicated a higher conductivity for electrodeposited compared with dip-coated CoFe2O4 with enhanced device performance. Moreover, bending and chronoamperometry studies suggest excellent durability of the catalytic electrode for long-term use. The energy storage behavior of CoFe2O4 showed high specific capacitance of 768 F/g at a current density of 0.5 A/g and maintained about 80% retention after 10,000 cycles. These results demonstrate the competitiveness and multifunctional applicability of the CoFe2O4 spinel to be used for energy generation and storage devices.

N Stobie, B Duffy, DE McCormack, J Colreavy, M Hidalgo, P McHale, SJ Hinder (2008)Prevention of Staphylococcus epidermidis biofilm formation using a low-temperature processed silver-doped phenyltriethoxysilane sol-gel coating, In: BIOMATERIALS29(8)pp. 963-969 ELSEVIER SCI LTD
SJ Hinder, SD Connell, MC Davies, CJ Roberts, SJB Tendler, PM Williams (2002)Compositional mapping of self-assembled monolayers derivatized within microfluidic networks, In: LANGMUIR18(8)pp. 3151-3158 AMER CHEMICAL SOC
N Stobie, B Duffy, J Colreavy, P McHale, SJ Hinder, DE McCormack (2010)Dual-action hygienic coatings: Benefits of hydrophobicity and silver ion release for protection of environmental and clinical surfaces, In: JOURNAL OF COLLOID AND INTERFACE SCIENCE345(2)pp. 286-292 ACADEMIC PRESS INC ELSEVIER SCIENCE
M. AlKetbi, K. Polychronopoulou, Abdallah. F. Zedan, V. Sebastián, Mark A. Baker, A. AlKhoori, M.A. Jaoude, O. Alnuaimi, Steve S. Hinder, Anjana Tharalekshmy, Amina S. AlJaber (2018)Tuning the activity of Cu-containing rare earth oxide catalysts for CO oxidation reaction: Cooling while heating paradigm in microwave-assisted synthesis, In: Materials Research Bulletin108pp. 142-150 Elsevier

(Ce-La-xCu)O2 catalysts with low (3 at.%) and high (10 at.%) Cu content were prepared by conventional microwave (MW) and enhanced microwave methods where air cooling (AC), while heating, was applied. The catalysts were tested for the CO oxidation reaction in the 25–500 °C range using 4%CO/20%O2/He feed gas. Varying spectroscopic, microscopic and catalytic studies were used to probe the effect of synthesis on the nanostructure and the CO oxidation performance. It was found that the synthesis method adopted impacts on the extent of the Cu doping into the (Ce-La)O2 fluorite lattice, hence leading to one and two phases system in the case of catalyst prepared through enhanced (AC) and conventional (MW) microwave methods, respectively. Furthermore, only Ce4+ species were found on the surface of the (Ce-La-10Cu)O2 catalysts synthesized using MW and AC (XPS studies), whereas oxygen vacant sites which are associated with Ce3+ ions were indicated in the sub-surface/bulk (Raman studies). Ultimately, the catalysts with the low and high Cu loading, prepared under the AC-promoted microwave method, presented a superior performance against CO oxidation, exhibiting an overall improvement of the catalytic activity by 16% and 32%, respectively.

Chen Zhao, Chunyang Zhang, Sanket Bhoyate, Pawan Kahol, Nikolaos Kostoglou, Christian Mitterer, Steven Hinder, Mark Baker, Georgios Constantinides, Kyriaki Polychronopoulou, Claus Rebholz, Ram Gupta (2019)Nanostructured Fe-Ni Sulfide: A Multifunctional Material for Energy Generation and Storage, In: Catalysts MDPI AG
V Etacheri, MK Seery, SJ Hinder, SC Pillai (2012)Nanostructured Ti(1-x)S(x)O(2-y)N(y) heterojunctions for efficient visible-light-induced photocatalysis., In: Inorg Chem51(13)pp. 7164-7173

Highly visible-light-active S,N-codoped anatase-rutile heterojunctions are reported for the first time. The formation of heterojunctions at a relatively low temperature and visible-light activity are achieved through thiourea modification of the peroxo-titania complex. FT-IR spectroscopic studies indicated the formation of a Ti(4+)-thiourea complex upon reaction between peroxo-titania complex and thiourea. Decomposition of the Ti(4+)-thiourea complex and formation of visible-light-active S,N-codoped TiO(2) heterojunctions are confirmed using X-ray diffraction, Raman spectroscopy, transmission electron microscopy, and UV/vis spectroscopic studies. Existence of sulfur as sulfate ions (S(6+)) and nitrogen as lattice (N-Ti-N) and interstitial (Ti-N-O) species in heterojunctions are identified using X-ray photoelectron spectroscopy (XPS) and FT-IR spectroscopic techniques. UV-vis and valence band XPS studies of these S,N-codoped heterojunctions proved the fact that the formation of isolated S 3p, N 2p, and Π* N-O states between the valence and conduction bands are responsible for the visible-light absorption. Titanium dioxide obtained from the peroxo-titania complex exists as pure anatase up to a calcination temperature as high as 900 °C. Whereas, thiourea-modified samples are converted to S,N-codoped anatase-rutile heterojunctions at a temperature as low as 500 °C. The most active S,N-codoped heterojunction 0.2 TU-TiO(2) calcined at 600 °C exhibits a 2-fold and 8-fold increase in visible-light photocatalytic activities in contrast to the control sample and the commercial photocatalyst Degussa P-25, respectively. It is proposed that the efficient electron-hole separation due to anatase to rutile electron transfer is responsible for the superior visible-light-induced photocatalytic activities of S,N-codoped heterojunctions.

K Polychronopoulou, C Rebholz, Mark Baker, L Theodorou, NG Demas, Steven Hinder, AA Polycarpou, CC Doumanidis, K Boebel (2008)Nanostructure, mechanical and tribological properties of reactive magnetron sputtered TiCx coatings, In: DIAMOND AND RELATED MATERIALS17(12)pp. 2054-2061 ELSEVIER SCIENCE SA
N Stobie, B Duffy, SJ Hinder, P McHale, DE McCormack (2009)Silver doped perfluoropolyether-urethane coatings: Antibacterial activity and surface analysis, In: COLLOIDS AND SURFACES B-BIOINTERFACES72(1)pp. 62-67 ELSEVIER SCIENCE BV
UV Shah, JV Parambil, DR Williams, SJ Hinder, JYY Heng (2015)Preparation and characterisation of 3D nanotemplates for protein crystallisation, In: POWDER TECHNOLOGY282pp. 10-18 ELSEVIER SCIENCE BV
DW Synnott, MK Seery, SJ Hinder, G Michlits, SC Pillai (2013)Anti-bacterial activity of indoor-light activated photocatalysts, In: APPLIED CATALYSIS B-ENVIRONMENTAL130pp. 106-111 ELSEVIER SCIENCE BV
Steven Hinder, John Watts, GC Simmons, C Lowe (2008)An investigation of the distribution of minor components in complex polymeric paint formulations using ToF-SIMS depth profiling, In: SURFACE AND INTERFACE ANALYSIS40(3-4)pp. 436-440 JOHN WILEY & SONS LTD
R Ho, SJ Hinder, JF Watts, SE Dilworth, DR Williams, JYY Heng (2010)Determination of surface heterogeneity of D-mannitol by sessile drop contact angle and finite concentration inverse gas chromatography, In: INTERNATIONAL JOURNAL OF PHARMACEUTICS387(1-2)pp. 79-86 ELSEVIER SCIENCE BV
NJ Bright, Roger Webb, Steven Hinder, Karen Kirkby, Neil Ward, John Watts, S Bleay, MJ Bailey (2012)Determination of the deposition order of overlapping latent fingerprints and inks using Secondary Ion Mass Spectrometry (SIMS)., In: Anal Chem84(9)pp. 4083-4087 American Chemical Society

A new protocol using time-of-flight secondary ion mass spectrometry (ToF-SIMS) has been developed to identify the deposition order of a fingerprint overlapping an ink line on paper. By taking line scans of fragment ions characteristic of the ink molecules (m/z 358.2 and 372.2) where the fingerprint and ink overlap and by calculating the normalised standard deviation of the intensity variation across the line scan, it is possible to determine whether or not a fingerprint is above ink on a paper substrate. The protocol adopted works for a selection of fingerprints from four donors tested here and for a fingerprint that was aged for six months; for one donor, the very faint fingerprints could not be visualized using either standard procedures (ninhydrin development) or SIMS and therefore the protocol correctly gives an inconclusive result.

NT Nolan, MK Seery, SJ Hinder, LF Healy, SC Pillai (2010)A Systematic Study of the Effect of Silver on the Chelation of Formic Acid to a Titanium Precursor and the Resulting Effect on the Anatase to Rutile Transformation of TiO2, In: JOURNAL OF PHYSICAL CHEMISTRY C114(30)pp. 13026-13034 AMER CHEMICAL SOC
SJ Hinder, C Lowe, JT Maxted, JF Watts (2004)A ToF-SIMS investigation of a buried polymer/polymer interface exposed by ultra-low-angle microtomy, In: SURFACE AND INTERFACE ANALYSIS36(12)pp. 1575-1581 JOHN WILEY & SONS LTD

The interfacial region of a model, multilayer coating system on an aluminium substrate has been investigated by high resolution time-of-flight secondary ion mass spectrometry (ToF-SIMS). Employing ultra-low-angle microtomy (ULAM), the interface between a poly(vinylidene difluoride) (PVdF) based topcoat and a poly(urethane) (PU) based primer ‘buried’ over 20μm below the PVdF topcoat’s air/coating surface was exposed. Imaging ToF-SIMS and subsequent post-processing extraction of mass spectra of the ULAM exposed interface region and the PVdF topcoat and PU primer bulks indicates that the material composition of the polymer-polymer interface region is substantially different to that of the bulk PVdF and PU coatings. Analysis of the negative ion mass spectra obtained from the PVdF/PU interface reveals the presence of a methacrylate based component or additive at the interface region. Reviewing the topcoat and primer coating formulations reveals the PVdF topcoat formulation contains methyl methacrylate (MMA)/ethyl acrylate (EA) acrylic co-polymer components. Negative ion ToF-SIMS analysis of an acrylic co-polymer confirms it is these components that are observed at the PVdF/PU interface. Post-processing extraction of ToF-SIMS images based on the major ions of the MMA/EA co-polymers reveals these components are observed in high concentration at the extremities of the PVdF coating i.e. at the polymer-polymer interface but are also observed to be distributed evenly throughout the bulk of the PVdF topcoat. These findings confirms that a fraction of the MMA/EA acrylic co-polymers in the formulation segregate to the topcoat-primer interface where they enhance the adhesive properties exhibited by the PVdF topcoat towards the underlying PU primer substrate.

G Subramanian, P Nalawade, SJ Hinder, SC Pillai, H Prakash (2015)Nickel azamacrocyclic complex activated persulphate based oxidative degradation of methyl orange: recovery and reuse of complex using adsorbents, In: RSC ADVANCES5(40)pp. 31716-31724 ROYAL SOC CHEMISTRY
S Gravani, K Polychronopoulou, V Stolojan, Q Cui, PN Gibson, SJ Hinder, Z Gu, CC Doumanidis, MA Baker, C Rebholz (2010)Growth and characterization of ceria thin films and Ce-doped gamma-Al2O3 nanowires using sol-gel techniques, In: NANOTECHNOLOGY21(46)465606 IOP PUBLISHING LTD

γ-Al2O3 is a well known catalyst support. The addition of Ce to γ-Al2O3 is known to beneficially retard the phase transformation of γ-Al2O3 to α-Al2O3 and stabilize the γ-pore structure. In this work, Ce-doped γ-Al2O3 nanowires have been prepared by a novel method employing an anodic aluminium oxide (AAO) template in a 0.01 M cerium nitrate solution, assisted by urea hydrolysis. Calcination at 500 °C for 6 h resulted in the crystallization of the Ce-doped AlOOH gel to form Ce-doped γ-Al2O3 nanowires. Ce3 + ions within the nanowires were present at a concentration of < 1 at.%. On the template surface, a nanocrystalline CeO2 thin film was deposited with a cubic fluorite structure and a crystallite size of 6–7 nm. Characterization of the nanowires and thin films was performed using scanning electron microscopy, transmission electron microscopy, electron energy loss spectroscopy, x-ray photoelectron spectroscopy and x-ray diffraction. The nanowire formation mechanism and urea hydrolysis kinetics are discussed in terms of the pH evolution during the reaction. The Ce-doped γ-Al2O3 nanowires are likely to find useful applications in catalysis and this novel method can be exploited further for doping alumina nanowires with other rare earth elements.

M Audronis, SJ Hinder, P Mack, V Bellido-Gonzalez, D Bussey, A Matthews, MA Baker (2011)A comparison of reactive plasma pre-treatments on PET substrates by Cu and Ti pulsed-DC and HIPIMS discharges, In: Thin Solid Films520(5)pp. 1564-1570 Elsevier

PET web samples have been treated by magnetically enhanced glow discharges powered using either medium frequency pulse direct current (p-DC) or low frequency high power pulse (HIPIMS) sources. The plasma pre-treatment processes were carried out in an Ar–O2 atmosphere using either Cu or Ti sputter targets. XPS, AFM and sessile drop water contact angle measurements have been employed to examine changes in surface chemistry and morphology for different pre-treatment process parameters. Deposition of metal oxide onto the PET surface is observed as a result of the sputter magnetron-based glow discharge web treatment. Using the Cu target, both the p-DC and HIPIMS processes result in the formation of a thin CuO layer (with a thickness between 1 and 11 nm) being deposited onto the PET surface. Employing the Ti target, both p-DC and HIPIMS processes give rise to a much lower concentration of Ti (< 5 at.%), in the form of TiO2 on the PET treated surface. The TiO2 is probably distributed as an island-like distribution covering the PET surface. Presence of Cu and Ti oxide constituents on the treated PET is beneficial in aiding the adhesion but alone (i.e. without oxygen plasma activation) is not enough to provide very high levels of hydrophilicity as is clear from sessile drop water contact angle measurements on aged samples. Exposure to the plasma treatments leads to a small amount of roughening of the substrate surface, but the average surface roughness in all cases is below 2.5 nm. The PET structure at the interface with a coating is mostly or wholly preserved. The oxygen plasma treatment, metal oxide deposition and surface roughening resulting from the HIPIMS and p-DC treatments will promote adhesion to any subsequent thin film that is deposited immediately following the plasma treatment.

Kyriaki Polychronopoulou, Nikolaos D Charisiou, Kyriakos N Papageridis, Victor Sebastian, Steven Hinder, Aasif A Dabbawala, Ayesha A. AlKhoori, Mark Baker, Maria A. Goula (2018)The effect of Ni addition onto a Cu-based ternary support on the H₂ production over glycerol steam reforming reaction, In: Nanomaterials8(11)931pp. 1-27 MDPI

In the present study, Ni/Ce-Sm-xCu (x = 5, 7, 10 at.%) catalysts were prepared using microwave radiation coupled with sol-gel and followed by wetness impregnation method for the Ni incorporation. Highly dispersed nanocrystallites of CuO and NiO on the Ce-Sm-Cu support were found. Increase of Cu content seems to facilitate the reducibility of the catalyst according to the H₂ temperature-programmed reduction (H₂-TPR). All the catalysts had a variety of weak, medium and strong acid/basic sites that regulate the reaction products. All the catalysts had very high XC3H8O3 for the entire temperature (400–750 °C) range; from ≈84% at 400 °C to ≈94% at 750 °C. Ni/Ce-Sm-10Cu catalyst showed the lowest XC3H8O3-gas implying the Cu content has a detrimental effect on performance, especially between 450–650 °C. In terms of H₂ selectivity (SH2) and H₂ yield (YH2), both appeared to vary in the following order: Ni/Ce-Sm-10Cu ˃ Ni/Ce-Sm-7Cu ˃ Ni/Ce-Sm-5Cu, demonstrating the high impact of Cu content. Following stability tests, all the catalysts accumulated high amounts of carbon, following the order Ni/Ce-Sm-5Cu ˂ Ni/Ce-Sm-7Cu ˂ Ni/Ce-Sm-10Cu (52, 65 and 79 wt.%, respectively) based on the thermogravimetric analysis (TGA) studies. Raman studies showed that the incorporation of Cu in the support matrix controls the extent of carbon graphitization deposited during the reaction at hand.

ME Özsan, PJ Sellin, P Veeramani, SJ Hinder, MLT Monnier, G Prekas, A Lohstroh, MA Baker (2010)Chemical etching and surface oxidation studies of cadmium zinc telluride radiation detectors, In: Surface and Interface Analysis42(6-7)pp. 795-798 Wiley-Blackwell
V Etacheri, MK Seery, SJ Hinder, SC Pillai (2010)Highly Visible Light Active TiO2-xNx Heterojunction Photocatalysts, In: CHEMISTRY OF MATERIALS22(13)pp. 3843-3853 AMER CHEMICAL SOC
R Fagan, DE McCormack, SJ Hinder, SC Pillai (2016)Photocatalytic Properties of g-C3N4-TiO2 Heterojunctions under UV and Visible Light Conditions, In: MATERIALS9(4)ARTN 286 MDPI AG
UV Shah, D Olusanmi, AS Narang, MA Hussain, MJ Tobyn, SJ Hinder, JYY Heng (2015)Decoupling the Contribution of Surface Energy and Surface Area on the Cohesion of Pharmaceutical Powders, In: PHARMACEUTICAL RESEARCH32(1)pp. 248-259 SPRINGER/PLENUM PUBLISHERS
P Periyat, DE McCormack, SJ Hinder, SC Pillai (2009)One-Pot Synthesis of Anionic (Nitrogen) and Cationic (Sulfur) Codoped High-Temperature Stable, Visible Light Active, Anatase Photocatalysts, In: JOURNAL OF PHYSICAL CHEMISTRY C113(8)pp. 3246-3253 AMER CHEMICAL SOC
V Etacheri, G Michlits, MK Seery, SJ Hinder, SC Pillai (2013)A highly efficient TiO2-xCx nano-heterojunction photocatalyst for visible light induced antibacterial applications., In: ACS Appl Mater Interfaces

Visible-light-induced antibacterial activity of carbon-doped anatase-brookite titania nano-heterojunction photocatalysts are reported for the first time. These heterostructures were prepared using a novel low temperature (100 °C) non-hydrothermal low power microwave (300 W) assisted method. Formation of interband C 2p states was found to be responsible for the band gap narrowing of the carbon doped heterojunctions. The most active photocatalyst obtained after 60 minutes of microwave irradiation exhibits a 2-fold higher visible-light induced photocatalytic activity in contrast to the standard commercial photocatalyst Evonik-Degussa P-25. Staphylococcus aureus inactivation rate constant for carbon-doped nano-heterojunctions and the standard photocatalyst was 0.0023 and -0.0081 min-1 respectively. It is proposed that the photo-excited electrons (from the C 2p level) are effectively transferred from the conduction band of brookite to that of anatase causing efficient electron-hole separation, which is found to be responsible for the superior visible-light induced photocatalytic and antibacterial activities of carbon-doped anatase-brookite nano-heterojunctions.

MA Hughes, Y Fedorenko, RM Gwilliam, KP Homewood, RJ Curry, S Hinder, B Gholipour, DW Hewak, T-H Lee, SR Elliott (2014)Ion-implantation-enhanced chalcogenide-glass resistive-switching devices, In: Applied Physics Letters105(8)

We report amorphous GaLaSO-based resistive switching devices, with and without Pb-implantation before deposition of an Al active electrode, which switch due to deposition and dissolution of Al metal filaments. The devices set at 2-3 and 3-4 V with resistance ratios of 6 × 10 and 3 × 10 for the unimplanted and Pb-implanted devices, respectively. The devices reset under positive Al electrode bias, and Al diffused 40 nm further into GaLaSO in the unimplanted device. We attribute the positive reset and higher set bias, compared to devices using Ag or Cu active electrodes, to the greater propensity of Al to oxidise. © 2014 AIP Publishing LLC.

V Etacheri, MK Seery, SJ Hinder, SC Pillai (2011)Oxygen Rich Titania: A Dopant Free, High Temperature Stable, and Visible-Light Active Anatase Photocatalyst, In: ADVANCED FUNCTIONAL MATERIALS21(19)pp. 3744-3752 WILEY-V C H VERLAG GMBH
Izabela Jurewicz, Rosa Garriga, Matthew J Large, Jake Burn, Niki Bardi, Alice AK King, Eirini Velliou, John Watts, Steven Hinder, Edgar Muñoz, Alan B Dalton (2018)Functionalization of Silver Nanowire Transparent Electrodes with Self-Assembled 2-Dimensional Tectomer Nanosheets, In: ACS Applied Nano Materials1(8)pp. 3903-3912 American Chemical Society

Here, we describe the unusual self-assembly of amine-terminated oligoglycine peptides into extended two-dimensional sheets in the presence of silver nanowires. The resulting tectomer sheets are shown to have a strong affinity for the nanowires through a charge-transfer interaction as evidenced by X-ray photoelectron spectroscopy. We show that extended assemblies of metal-peptide hybrids offer additional augmentative functionalities, for instance, the tectomer sheets are hydrophobic in nature and act as a protective layer preventing oxidation and degradation of the nanowires when exposed to atmospheric conditions. Moreover, for silver nanowire percolating networks the presence of the peptide markedly increases the overall electrical conductivity through mechanical squeezing of wire-wire junctions in the network. The peptide-metal interface can be controlled by pH stimulus thus potentially offering new directions where silver nanowire assemblies are used for transparent electrodes ranging from antimicrobial coatings to biosensors.

V Kalarivalappil, CM Divya, W Wunderlich, SC Pillai, SJ Hinder, M Nageri, V Kumar, BK Vijayan (2016)Pd Loaded TiO2 Nanotubes for the Effective Catalytic Reduction of p-Nitrophenol, In: CATALYSIS LETTERS146(2)pp. 474-482 SPRINGER
DW Synnott, MK Seery, SJ Hinder, J Colreavy, SC Pillai (2013)Novel microwave assisted synthesis of ZnS nanomaterials, In: NANOTECHNOLOGY24(4)ARTN 04570 IOP PUBLISHING LTD
SJ Hinder, C Lowe, JF Watts (2007)An XPS and ToF-SIMS investigation of the outermost nanometres of a poly(vinylidene difluoride) coating, In: PROGRESS IN ORGANIC COATINGS60(3)pp. 255-261 ELSEVIER SCIENCE SA
N.D. Charisiou, G. Siakavelas, L. Tzounis, V. Sebastian, A. Monzon, M.A. Baker, S.J. Hinder, K. Polychronopoulou, I.V. Yentekakis, M.A. Goula (2018)An in depth investigation of deactivation through carbon formation during the biogas dry reforming reaction for Ni supported on modified with CeO2 and La2O3 zirconia catalysts, In: International Journal of Hydrogen Energy43(41)pp. 18955-18976 Elsevier

The dry reforming of biogas on a Ni catalyst supported on three commercially available materials (ZrO2, La2O3-ZrO2 and CeO2-ZrO2), has been investigated, paying particular attention to carbon deposition. The DRM efficiency of the catalysts was studied in the temperature range of 500-800oC at three distinct space velocities, and their time-on-stream stability at four temperatures (550, 650, 750 and 800oC) was determined for 10 or 50 h operation. The morphological, textural and other physicochemical characteristics of fresh and spent catalysts together with the amount and type of carbon deposited were examined by a number of techniques including BET-BJH method, CO2 and NH3-TPD, XPS, SEM, TEM, STEM-HAADF, Raman spectroscopy, and TGA/DTG. The impact of the La2O3 and CeO2 modifiers on the DRM performance and time-on-stream stability of the Ni/ZrO2 catalyst was found to be very beneficial: up to 20 and 30% enhancement in CH4 and CO2 conversions respectively, accompanied with a CO-enriched syngas product, while the 50 h time-on-stream catalytic performance deterioration of ~30-35% on Ni/ZrO2 was limited to less than ~15-20% on the La2O3 and CeO2 modified samples. Their influence on the amount and type of carbon formed was substantial: it was revealed that faster oxidation of the deposited carbon at elevated temperatures occurs on the modified catalysts. Correlations between the La2O3 and CeO2-induced modifications on the surface characteristics and physicochemical properties of the catalyst with their concomitant support-mediated effects on the overall DRM performance and carbon deposition were revealed.

SJ Hinder, C Lowe, JT Maxted, JE Watts (2005)Migration and segregation phenomena of a silicone additive in a multilayer organic coating, In: PROGRESS IN ORGANIC COATINGS54(2)pp. 104-112 ELSEVIER SCIENCE SA

The migration and segregation of a minor silicone containing additive in a multilayer, organic coating system has been investigated by X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The silicone containing additive employed was the most compatible thermally stable, polyester modified poly(dimethyl siloxane) (PDMS) flow agent. A polyester/polyurethane (PU) based primer and a poly(vinylidene difluoride) (PVdF) based topcoat on an aluminium substrate were used as a model, multilayer, organic coating system. XPS and SIMS characterisation of the PU primer formulation (with and without addition of the PDMS based flow agent), confirmed that the PDMS based flow agent segregated to the PU primers air/coating surface. Characterisation of the PVdF topcoats air/coating surface, after application and curing over the PU primers, revealed the presence of the PDMS based flow agent at the PVdF air/coating surface when the topcoat was applied to the PU primer containing the PDMS based flow agent. Ultra-low-angle microtomy (ULAM) was employed to produce an ultra-low-angle taper that passes through the entire thickness of the PVdF topcoat (~20 µm). XPS linescan analysis along the ULAM taper indicated that the PDMS based flow agent had migrated from the PU primer surface into the bulk of the PVdF topcoat. Analysis of the shape of the silicon concentration profile revealed the existence of a silicon concentration gradient and indicated that the PDMS based flow agent was segregating towards the PVdF topcoats air/coating surface. Such migration and segregation phenomena have major implications for formulators in the coatings/paint industries.

SFA Sani, GA Mahdiraji, ASS Shafiqah, GW Grime, V Palitsin, SJ Hinder, N Tamchek, HAA Rashid, MJ Maah, JF Watts, DA Bradley (2015)XPS and PIXE Analysis of Doped Silica Fibre for Radiation Dosimetry, In: JOURNAL OF LIGHTWAVE TECHNOLOGY33(11)pp. 2268-2278 IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
P Periyat, SC Pillai, DE McCormack, J Colreavy, SJ Hinder (2008)Improved high-temperature stability and sun-light-driven photocatalytic activity of sulfur-doped anatase TiO(2), In: JOURNAL OF PHYSICAL CHEMISTRY C112(20)pp. 7644-7652 AMER CHEMICAL SOC
SJ Hinder, C Lowe, JT Maxted, JF Watts (2005)The morphology and topography of polymer surfaces and interfaces exposed by ultra-low-angle microtomy, In: JOURNAL OF MATERIALS SCIENCE40(2)pp. 285-293 SPRINGER

The ultra-low-angle microtomy (ULAM) technique has been developed to impart a cross-sectional, ultra-low-angle taper through polymeric materials such as coatings and paints. ULAM employs a conventional rotary microtome in combination with high-precision, angled sectioning blocks to fabricate the ultra-low-angle tapers. Subsequent investigation of the tapers produced by ULAM may be used in conjunction with X-ray photoelectron spectroscopy (XPS) or time-of-flight secondary ion mass spectrometry (ToF-SIMS), for compositional depth profiling or ‘buried’ interface analysis. Variation in the selection of the ULAM taper angle and/or the analysis interval size employed enables depth resolution at the nanometre or micrometre scales to be achieved. In the work described here scanning electron microscopy (SEM) and atomic force microscopy (AFM) have been employed to investigate the morphology and topography of the surfaces resulting from the ULAM tapering process. It is demonstrated that a correctly mounted polymeric sample, sectioned with a sharp microtome knife, displays little perturbation of the resulting polymeric surface after ULAM processing. Additionally, SEM analysis of the interface region between a poly(vinylidene fluoride) (PVdF) topcoat and polyurethane (PU) primer exposed by ULAM processing reveals that the interface region between the two coatings possesses a well-defined boundary. No evidence of polymeric smearing across the interface is observed. XPS compositional depth profiling across a ‘buried’ PVdF/PU interface, exposed by ULAM processing, is employed to demonstrate the utility of the ULAM technique.

SC Pillai, P Periyat, R George, DE McCormack, MK Seery, H Hayden, J Colreavy, D Corr, SJ Hinder (2007)Synthesis of high-temperature stable anatase TiO2 photocatalyst, In: JOURNAL OF PHYSICAL CHEMISTRY C111(4)pp. 1605-1611 AMER CHEMICAL SOC
Ignacio Martín-Fabiani, Ming Liang Koh, Florent Dalmas, Katrin Elidottir, Steven J. Hinder, Izabela Jurewicz, Muriel Lansalot, Elodie Bourgeat-Lami, Joseph L. Keddie (2018)Design of Waterborne Nanoceria/Polymer Nanocomposite UV-Absorbing Coatings: Pickering versus Blended Particles, In: ACS Applied Nano Materials1(8)pp. 3956-3968 American Chemical Society

Nanoparticles of cerium dioxide (or nanoceria) are of interest because of their oxygen buffering, photocatalytic ability, and high UV absorption. For applications, the nanoceria can be incorporated in a polymer binder, but questions remain about the link between the nanoparticle distribution and the resulting nanocomposite properties. Here, the thermal, mechanical and optical properties of polymer/ceria nanocomposites are correlated with their nanostructures. Specifically, nanocomposites made from waterborne Pickering particles with nanoceria shells are compared to nanocomposites made from blending the equivalent surfactant-free copolymer particles with nanoceria. Two types of nanoceria (protonated or citric acid-coated) are compared in the Pickering particles. A higher surface coverage is obtained with the protonated ceria, which results in a distinct cellular structure with nanoceria walls within the nanocomposite. In the blend of particles, a strong attraction between the protonated nanoceria and the acrylic acid groups of the copolymer likewise leads to a cellular structure. This structure offers transparency in the visible region combined with strong UV absorption, which is desired for UV blocking coating applications. Not having an attraction to the polymer, the citric acid-coated nanoceria forms agglomerates that lead to undesirable light scattering in the nanocomposite and yellowing. This latter type of nanocomposite coating is less effective in protecting substrates from UV damage but provides a better barrier to water. This work shows how the nanoparticle chemical functionalization can be used to manipulate the structure and to tailor the properties of UV-absorbing barrier coatings.

SJ Hinder, C Lowe, JT Maxted, C Perruchot, JE Watts (2005)Intercoat adhesion failure in a multilayer organic coating system: An X-ray photoelectron spectroscopy study, In: PROGRESS IN ORGANIC COATINGS54(1)pp. 20-27 ELSEVIER SCIENCE SA

The strength of intercoat adhesion exhibited between a series of polyester/polyurethane (PU) based primer formulations and a standard poly(vinylidene difluoride) (PVdF) based topcoat formulation has been investigated by X-ray photoelectron spectroscopy (XPS). An initial XPS study of changes in surface elemental composition (induced by variation of the peak metal temperature (PMT) achieved during thermal curing), on a subset of the PU primers employed, indicates that beyond a PMT of 232°C changes in PU primer surface composition are negligible. A reference PU primer coating formulation and four variations of this formulation, produced by including, excluding or substituting components/additives in the reference formulation, are characterised by XPS. The PU primer formulation in which a flow agent additive is included exhibits segregation of the flow agent to the primer surface. The PU primer and PVdF topcoat intercoat adhesion failure surfaces resulting from failure at or near the PVdF/PU interface as a result of a peel test are also characterised by XPS. Additionally the PVdF topcoat air-coating surface is characterised by XPS. The interface analyses for the flow agent containing PU primer formulation indicates stripping of the flow agent layer from the PU primer and transfer of the flow agent to the PVdF topcoat interfacial failure surface. Similarly, PU primer formulations in which the concentrations of a crosslinking resin are changed demonstrate that the transfer of carbon and oxygen containing materials from the PU primer to the PVdF topcoat occurs, due to insufficient crosslinking of the polyester component of the PU primer formulation. These results suggest a correlation between the nitrogen concentration at the PU primer surface and the strength of the intercoat adhesion exhibited by the PU primer towards the PVdF topcoat.

JV Parambil, SK Poornachary, SJ Hinder, RBH Tan, JYY Heng (2015)Establishing template-induced polymorphic domains for API crystallisation: the case of carbamazepine, In: CRYSTENGCOMM17(33)pp. 6384-6392 ROYAL SOC CHEMISTRY
N.D. Charisiou, K.N. Papageridis, G. Siakavelas, V. Sebastian, S.J. Hinder, M.A. Baker, K. Polychronopoulou, M.A. Goula (2018)The influence of SiO2 doping on the Ni/ZrO2 supported catalyst for hydrogen production through the glycerol steam reforming reaction, In: Catalysis Today319pp. 206-219 Elsevier

The glycerol steam reforming (GSR) reaction for H2 production was studied comparing the performance of Ni supported on ZrO2 and SiO2-ZrO2 catalysts. The surface and bulk properties were determined by ICP, BET, XRD, TPD, TPR, TPO, XPS, SEM and STEM-HAADF. It was suggested that the addition of SiO2 stabilizes the ZrO2 monoclinic structure, restricts the sintering of nickel particles and strengthens the interaction between Ni2+ species and support. It also removes the weak acidic sites and increases the amount of the strong acidic sites, whereas it decreases the amount of the basic sites. Furthermore, it influences the gaseous products’ distribution by increasing H2 yield and not favouring the transformation of CO2 in CO. Thus, a high H2/CO ratio can be achieved accompanying by negligible value for CO/CO2. From the liquid products quantitative analysis, it was suggested that acetone and acetaldehyde were the main products for the Ni/Zr catalyst, for 750oC, whereas for the Ni/SiZr catalyst allyl alcohol was the only liquid product for the same temperature. It was also concluded that the Ni/SiZr sample seems to be more resistant to deactivation however, for both catalysts a substantial amount of carbon exists on the catalytic surface in the shape of carbon nanotubes and amorphous carbon.

A Foerster, I Holowacz, GBS Kumar, S Anandakumar, JG Wall, M Wawrzynska, M Paprocka, A Kantor, H Kraskiewicz, S Olsztynska-Janus, SJ Hinder, D Bialy, H Podbielska, M Kopaczynska (2016)Stainless steel surface functionalization for immobilization of antibody fragments for cardiovascular applications, In: JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART A104(4)pp. 821-832 WILEY-BLACKWELL
A Danesh, MC Davies, SJ Hinder, CJ Roberts, SJB Tendler, PM Williams, MJ Wilkins (2000)Surface characterization of aspirin crystal planes by dynamic chemical force microscopy, In: ANALYTICAL CHEMISTRY72(15)pp. 3419-3422 AMER CHEMICAL SOC
NS Leyland, J Podporska-Carroll, J Browne, SJ Hinder, B Quilty, SC Pillai (2016)Highly Efficient F, Cu doped TiO2 anti-bacterial visible light active photocatalytic coatings to combat hospital-acquired infections, In: SCIENTIFIC REPORTS6ARTN 24770 NATURE PUBLISHING GROUP
Camila Zequine, Sanket Bhoyate, Khamis Siam, Pawan K. Kahol, Nikolaos Kostoglou, Christian Mitterer, Steven Hinder, Mark Baker, Georgios Constantinides, Claus Rebholz, Gautam Gupta, Xianglin Li, Ram K. Gupta (2018)Needle grass array of nanostructured nickel cobalt sulfide electrode for clean energy generation, In: Surface and Coatings Technology354pp. 306-312 Elsevier

Significant efforts have been focused on the search of earth-abundant elements to solve growing energy issues and to provide bifunctional behavior for both hydrogen and oxygen evolution reaction. Mixed transition metals could provide promising synergistic electrochemical properties and serve as bi-catalyst for overall water splitting process. In this study, a needle grass array of nanostructured nickel cobalt sulfide (NiCo2S4) was synthesized using a hydrothermal process. The synthesized NiCo2S4 electrodes showed promising electrocatalytic activity with a low overpotential of 148 mV and 293 mV for hydrogen and oxygen evolution reactions, respectively. The electrolyzer cell consisting of two NiCo2S4 electrodes displayed excellent performance with high electrochemical stability and low overall cell potential of 1.61 V to achieve a current density of 10 mA/cm2. Our study suggests that mixed transition metal chalcogenides such as NiCo2S4 could be used as efficient and stable electrocatalyst for overall water splitting process.

M Constantinou, V Stolojan, KP Rajeev, S Hinder, B Fisher, TD Bogart, BA Korgel, M Shkunov (2015)Interface Passivation and Trap Reduction via a Solution-Based Method for Near-Zero Hysteresis Nanowire Field-Effect Transistors, In: ACS APPLIED MATERIALS & INTERFACES7(40)pp. 22115-22120 AMER CHEMICAL SOC

In this letter, we demonstrate a solution-based method for a one-step deposition and surface passivation of the as-grown silicon nanowires (Si NWs). Using N,N-dimethylformamide (DMF) as a mild oxidizing agent, the NWs' surface traps density was reduced by over 2 orders of magnitude from 1×10(13) cm(-2) in pristine NWs to 3.7×10(10) cm(-2) in DMF-treated NWs, leading to a dramatic hysteresis reduction in NW field-effect transistors (FETs) from up to 32 V to a near-zero hysteresis. The change of the polyphenylsilane NW shell stoichiometric composition was confirmed by X-ray photoelectron spectroscopy analysis showing a 35% increase in fully oxidized Si4+ species for DMF-treated NWs compared to dry NW powder. Additionally, a shell oxidation effect induced by DMF resulted is a more stable NW FET performance with steady transistor currents and only 1.5 V hysteresis after 1000 h of air exposure

ND Charisiou, KN Papageridis, G Siakavelas, L Tzounis, K Kousi, Mark Baker, Steven Hinder, VS Cabeza, K Polychronopoulou, MA Goula (2017)Glycerol Steam Reforming for Hydrogen Production over Nickel Supported on Alumina, Zirconia and Silica Catalysts, In: Topics in Catalysis60(15-16)pp. 1226-1250 Springer Verlag

The aim of the work was to investigate the influence of support on the catalytic performance of Ni catalysts for the glycerol steam reforming reaction. Nickel catalysts (8 wt%) supported on Al2O3, ZrO2, SiO2 were prepared by the wet impregnation technique. The catalysts’ surface and bulk properties, at their calcined, reduced and used forms, were determined by ICP, BET, XRD, NH3-TPD, CO2-TPD, TPR, XPS, TEM, TPO, Raman, SEM techniques. The Ni/Si sample, even if it was less active for T

K Polychronopoulou, AF Zedan, MS Katsiotis, Mark Baker, AA AlKhoori, SY AlQaradawi, Steven Hinder, S AlHassan (2017)Rapid Microwave Assisted Sol-Gel Synthesis of CeO2 and CexSm1-xO2 Nanoparticle Catalysts for CO Oxidation, In: Journal of Molecular Catalysis A: Chemical428pp. 41-55 Elsevier

CeO2 and CexSm1-xO2 nanoparticle mixed oxides have been synthesized by microwave assisted sol-gel (MW sol-gel) and conventional sol-gel (C sol-gel) synthesis carried out at 60oC (typical sol-gel) and 100oC (approaching the MW temperature). Different characterization techniques, namely, XRD, BET, Raman, SEM, FTIR, TEM, XPS, H2-TPR, CO2-TPD, and XPS have been employed to understand the process-structure-properties relationship of the catalysts. The CO oxidation performance has been determined both in the absence and in the presence of H2 in the feed gas stream. Microwave heating yields a more thermally stable precursor material, which preserves 75% of its mass up to 600oC, attributable to the different chemical nature of the precursor, compared to the typical sol-gel material with the same composition. Varying the synthesis method has no profound effect on the surface area of the materials, which is in the range 4-35m2/g. Conventional sol-gel synthesis performed at 60 and 100oC yields CeO2 particles with a crystallite size of 29 nm and 24 nm compared to 21-27 nm for MW sol-gel synthesis (at different power values). The MW sol-gel CexSm1-xO2 catalysts exhibit a smaller crystallite size (12-18 nm). The pure ceria nanoparticles were shown to have a stoichiometry of approximately CeO1.95. The presence of Ce3+ and Sm3+ in the mixed oxide particles facilitates the presence of oxygen vacant sites, confirmed by Raman. Oxygen mobile species have been traced using H2-TPR studies and a compressive lattice strain in the 0.45-1.9% range of the cubic CexSm1-xO2 lattice were found to be strongly correlated with the CO oxidation performance in the presence and absence of H2 in the oxidation feed stream. MW sol-gel synthesis led to more active CeO2 and Ce0.5Sm0.5O2 catalysts, demonstrated by T50 (temperature where 50% CO conversion is achieved), being reduced by 131 oC and 47 oC, respectively, compared to typical sol-gel catalysts. Conventional synthesis performed at 100oC leads to a CeO2 catalyst of initially higher activity at a certain temperature window (220-420oC), though with a slower increase of XCO with temperature compared to the MW one. MW sol-gel synthesized Ce0.8Sm0.2O2 exhibited a high performance (~90%) for CO oxidation over a period of more than 20 h in stream. In addition the effect of reaction temperature and contact time (W/F) on the activity of the CeO2-based materials for CO oxidation kinetics were investigated. The activation energy of the reaction was found to be in the 36-43 kJ/mole range depending on the catalyst composition.

NB Rahna, V Kalarivalappil, M Nageri, SC Pillai, SJ Hinder, V Kumar, BK Vijayan (2016)Stability studies of PbS sensitised TiO2 nanotube arrays for visible light photocatalytic applications by X-ray photoelectron spectroscopy (XPS), In: MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING42pp. 303-310 ELSEVIER SCI LTD
N.D. Charisiou, K.N. Papageridis, L. Tzounis, V. Sebastian, S.J. Hinder, M.A. Baker, M. AlKetbi, K. Polychronopoulou, M.A. Goula (2018)Ni supported on CaO-MgO-Al 2 O 3 as a highly selective and stable catalyst for H 2 production via the glycerol steam reforming reaction, In: International Journal of Hydrogen Energy Elsevier

A comparative study of the GSR performance for Ni/CaO-MgO-Al2O3 and Ni/Al2O3 catalysts is reported. Catalysts were synthesized applying the wet impregnation method at a constant metal loading (8 wt %). Synthesized samples were characterized by N2 adsorption/desorption, ICP, BET, XRD, NH3-TPD, CO2-TPD, H2-TPR, XPS, TEM, STEM-HAADF and EDS. The carbon deposited on their surface under reaction conditions was characterized by TPO, Raman and TEM. It was proven that the use of CaO-MgO as alumina modifiers leads to smaller nickel species crystallite size, increased basicity and surface amount of Ni0 phase. Thus, it increases the conversion to gaseous products favoring H2 and CO2 production to the detriment of CO formation, by enhancing the water gas-shift (WGS) reaction. No liquid products were produced by the Ni/modAl catalyst over 550 °C, whereas time on stream results confirmed that deactivation can be prevented, as apart from decreasing the amount of coke deposition the nature of carbon was altered towards less graphitic and more defective structures.

WR Zhang, SJ Hinder, R Smith, C Lowe, JF Watts (2010)An investigation of the effect of pigment on the degradation of a naturally weathered polyester coating, In: Journal of Coatings Technology Researchpp. 1-14
MB Fisher, DA Keane, P Fernandez-Ibanez, J Colreavy, SJ Hinder, KG McGuigan, SC Pillai (2013)Nitrogen and copper doped solar light active TiO2 photocatalysts for water decontamination, In: APPLIED CATALYSIS B-ENVIRONMENTAL130pp. 8-13 ELSEVIER SCIENCE BV
N.D. Charisiou, L. Tzounis, V. Sebastian, S.J. Hinder, M.A. Baker, K. Polychronopoulou, M.A. Goula (2018)Investigating the correlation between deactivation and the carbon deposited on the surface of Ni/Al2O3 and Ni/La2O3-Al2O3 catalysts during the biogas reforming reaction, In: Applied Surface Science Elsevier

Ni/Al2O3 and Ni/La2O-Al2O3 catalysts were investigated for the biogas reforming reaction using CH4/CO2 mixtures with minimal dilution. Stability tests at various reaction temperatures were conducted and TGA/DTG, Raman, STEM-HAADF, HR-TEM, XPS techniques were used to characterize the spent samples. Graphitized carbon allotrope structures, carbon nanotubes (CNTs) and amorphous carbon were formed on all samples. Metallic Ni0 was recorded for all (XPS), whereas a strong peak corresponding to Ni2O3/NiAl2O4, was observed for the Ni/Al sample (650–750°C). Stability tests confirm that the Ni/LaAl catalyst deactivates at a more gradual rate and is more active and selective in comparison to the Ni/Al for all temperatures. The Ni/LaAl exhibits good durability in terms of conversion and selectivity, whereas the Ni/Al gradually loses its activity in CH4 and CO2 conversion, with a concomitant decrease of the H2 and CO yield. It can be concluded that doping Al2O3 with La2O3 stabilizes the catalyst by (a) maintaining the Ni0 phase during the reaction, due to higher dispersion and stronger active phase-support interactions, (b) leading to a less graphitic and more defective type of deposited carbon and (c) facilitating the deposited carbon gasification due to the enhanced CO2 adsorption on its increased surface basic sites.

M Abi Jaoude, K Polychronopolou, SJ Hinder, MS Katsiotis, MA Baker, YE Greish, SM Alhassan (2016)Synthesis and properties of 1D Sm-doped CeO2 composite nanofibers fabricated using a coupled electrospinning and sol-gel methodology, In: Ceramics International42(9)pp. 10734-10744 Elsevier

Ce1-xSmxO2(x=0, 0.2, 0.5 and 0.8) nanofibers (NFs) were synthesized by coupling sol-gel with electrospinning and using poly-vinyl pyrrolidone (PVP) as the polymer medium, in an ethanol/water mixture. Control over the fabrication conditions was achieved through analysis of the most key synthetic factors, which include: (i) the applied field strength; (ii) the solution feed rate and (iii) the PVP content in the electrospinning solution. The optimum microstructural fiber morphology (high quality beeds-free fibers) was achieved using the following electrospinning parameters: an applied voltage of 18.5 kV, a 7 ml/hr of solution feed rate and a 12% (w/w) of PVP composition. Morphological features of the resulting fibers were examined by scanning electron microscopy (SEM). The average fiber diameter was typically found to be in the range of 200-1100 nm and 50-300 nm, before and after calcination at 500 oC, respectively. X-ray diffraction (XRD) results showed that the fluorite cubic structure was preserved for the entire Ce1-xSmxO2 compositional range studied, while elemental analysis using EELS and X-ray photoelectron spectroscopy (XPS) confirmed the purity of the bulk and surface composition of the fibers. Selected area electron diffraction (SAED) and high resolution transmission electron microscopy (HRTEM) proved that the NFs are highly crystalline. The thermal stability of the composite (polymer/inorganic nitrate salts) NFs was further investigated in an inert atmosphere (N2) using thermogravimetric analysis (TGA), which allowed the transformation process of the NFs from composite to oxide to be monitored. The reducibility of the metal oxide NFs (mobility of oxygen species in the fluorite cubic lattice) as well as their thermal stability in successive oxidation-reduction cycles was evaluated using temperature-programmed reduction in a H2 atmosphere (H2-TPR). Acidic-basic features of the NFs and powder surfaces were studied through temperature programmed desorption (TPD) using NH3 and CO2 as probe molecules, where weak, medium and strong acid sites were successfully traced with profound differences depending on the morphology. The NFs’ potential performance towards NH3 oxidation was also evaluated. Two types of basic sites, hydroxyl groups and surface lattice oxygen are present on the NFs, as probed by CO2 adsorption. Pyridine adsorption followed by infrared spectroscopy (Py-FT-IR) studies unveiled the more profound Lewis acid presence in Ce0.5Sm0.5O2 NFs compared to bulk powder Ce0.5Sm0.5O2.

Maitha Al Ketbi, Kyriaki Polychronopoulou, Maguy Abi Jaoude, Michalis A Vasiliades, Victor Sebastian, Steven J Hinder, Mark A Baker, Abdallah F Zedan, Angelos M Efstathiou (2019)Cu-Ce-La-Ox as efficient CO oxidation catalysts: effect of Cu content, In: Applied Surface Science Elsevier

Nanograins of Ce-La-xCu-O oxides, of 16 nm2 area size, are tested as materials towards the CO oxidation . Preservation of the cubic lattice structure following La3+ and Cu2+ metal cations doping is confirmed based on the powder X-ray diffraction and Raman studies. From XPS, the presence of mixed Ce3+/Ce4+ and Cu2+/Cu1+ oxidation states was confirmed, which was more profound in the low Cu-content Ce-La-xCu-O catalysts. Cu increases the concentration of oxygen vacant sites in the doped-CeO2 according to the Raman intensity ratio IOv/IF2g of 1.58 and 1.78 with the increase in copper content from 7 to 20 at.% as compared to the lower value of 0.44 for the Ce-La. The mobility of the surface and bulk lattice oxygen is further investigated using 16O/18O isotopic exchange (TIIE), and is found to be Cu at.% dependent. For the case of Ce-La-20Cu, the participation of the lattice oxygen (OL) in the reaction mechanism has been demonstrated using transient experiments. Accordingly, the specific rate (μmol CO m-2s-1) of the CO oxidation reaction is found to be higher for the Ce-La-20Cu and Ce-La-7Cu catalysts, corroborating thus the presence of more mobile/labile oxygen species in those ternary catalysts as opposed to the other lower copper compositions.

J Podporska-Carroll, A Myles, B Quilty, DE McCormack, R Fagan, SJ Hinder, DD Dionysiou, SC Pillai (2015)Antibacterial properties of F-doped ZnO visible light photocatalyst., In: J Hazard Mater

Nanocrystalline ZnO photocatalysts were prepared by a sol-gel method and modified with fluorine to improve their photocatalytic anti-bacterial activity in visible light. Pathogenic bacteria such as Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) were employed to evaluate the antimicrobial properties of synthesized materials. The interaction with biological systems was assessed by analysis of the antibacterial properties of bacteria suspended in 2% (w/w) powder solutions. The F-doping was found to be effective against S. aureus (99.99% antibacterial activity) and E. coli (99.87% antibacterial activity) when irradiated with visible light. Production of reactive oxygen species is one of the major factors that negatively impact bacterial growth. In addition, the nanosize of the ZnO particles can also be toxic to microorganisms. The small size and high surface-to-volume ratio of the ZnO nanoparticles are believed to play a role in enhancing antimicrobial activity.

NT Nolan, DW Synnott, MK Seery, SJ Hinder, A Van Wassenhoven, SC Pillai (2011)Effect of N-doping on the photocatalytic activity of sol-gel TiO2, In: Journal of Hazardous Materials
Roba Saab, Constantinos M. Damaskinos, Kyriaki Polychronopoulou, Angelos M. Efstathiou, Nikolaos Charisiou, Maria Goula, Steven J. Hinder, Mark A. Baker, Andreas Schiffer (2022)Ni/CNT/Zeolite-Y composite catalyst for efficient heptane hydrocracking: Steady-state and transient kinetic studies, In: Applied catalysis. A, General630 Elsevier B.V

The effect of integrating carbon nanotubes (CNTs) into a bi-functional Ni-Zeolite-Y catalyst was studied for the hydrocracking of heptane at 350 and 400 °C (total pressure of 5 bar). It was shown that the growth of CNTs on the surface of Ni-Zeolite-Y (Ni-ZY) results in enhanced stability and catalytic activity (conversion increased by 22% at 350 °C) compared to the conventional Ni-ZY. A significant increase in the initial transient kinetic rates of CH4 and C2H6 formation was also noticed. The CNT/Ni-ZY also showed reduced coke formation during the reaction as entailed by transient isothermal (400 °C) oxidation experiments. The formation of a crystalline NixCy phase on the zeolite surface was observed in the case of CNT/Ni-ZY, potentially responsible for its enhanced catalytic performance. This work demonstrates that the integration of CNTs in hydrocracking catalysts offers new opportunities for enhancing their catalytic activity, selectivity and coking resistance. [Display omitted] •Hydrocracking of heptane is performed using a CNT/Ni-Zeolite-Y catalyst.•Transient kinetic rates of CH4 and C2H6 formation were measured.•The inclusion of CNTs in the catalyst improved the conversion by 22% at 350 °C.•The inclusion of CNTs increased the selectivity towards propane by up to 75%.•The CNT-based catalyst reduced the amount of carbonaceous deposits by ≈ 20%.

Priyanka Ganguly, Snehamol Mathew, Laura Clarizia, Syam R. Kumar, Akinlolu Akande, Steven J. Hinder, Ailish Breen, Suresh C. Pillai (2020)Ternary Metal Chalcogenide Heterostructure (AgInS2-TiO2) Nanocomposites for Visible Light Photocatalytic Applications, In: ACS omega5(1)pp. 406-421 Amer Chemical Soc

Hybrid nanoarchffectures of AgInS2 and TiO2 photocatalysts were prepared by using a modified sol-gel method. The experimental results reveal that these nanocomposites display enhanced visible light absorption and effective charge carrier separation compared to their pristine parent samples (AgInS2 or TiO2). 0.5 wt % AgInS2 loading was found to be the optimum concentration for photocatalytic applications. More than 95% of doxycycline degradation was achieved within 180 min of solar light illumination. Similarly, the dopant concentrations at lower values (

Priyanka Ganguly, Snehamol Mathew, Laura Clarizia, Syam R. Kumar, A. Akande, Steven Hinder, Ailish Breen, Suresh C. Pillai (2019)Theoretical and experimental investigation of visible light responsive AgBiS2-TiO2 heterojunctions for enhanced photocatalytic applications, In: Applied catalysis. B, Environmental253pp. 401-418 Elsevier

The formation of heterostructure nanocomposite has been demonstrated to be an effective route to enhance the photocatalytic efficiency. Ternary chalcogenides (TC) with remarkable visible light absorption, are identified as an ideal candidate to form heterostructure with classical semiconductors such as TiO2. In the current investigation, novel heterojunctions of the AgBiS2-TiO2 composite were synthesised using a solvothermal technique. Computational analysis was utilised to study the electronic and optical properties of the pristine parent samples. The XRD results show the formation of the cubic phase of AgBiS2 and TiO2 is in tetragonal phase. The XPS and the TEM results illustrate the heterostructure formation. The UV-DRS pattern for all the composites shows enhanced visible light absorption due to the coupling of TC. The band gaps of the composites were decreased with increased doping levels. These materials were further studied for their photocatalytic efficiency, by photocatalytic degradation of Doxycycline, photocatalytic hydrogen generation and photocatalytic antimicrobial disinfection. The composite samples illustrated more than 95% degradation results within 180 min and showed about 3 log reductions of bacterial strains (E. coli and S. aureus) within 30 min of irradiation. The hydrogen production results were interesting as the AgBiS2 based composites illustrated a 1000-fold enhanced output. The enhanced photocatalytic activity is attributed to the decreased rate of recombination of the photogenerated excitons, as validated in the PL measurements. The scavenging experiments along with the theoretical analysis are used to define a plausible photocatalytic mechanism.

Snehamol Mathew, Priyanka Ganguly, Vignesh Kumaravel, John Harrison, Steven J. Hinder, John Bartlett, Suresh C. Pillai (2020)Effect of chalcogens (S, Se, and Te) on the anatase phase stability and photocatalytic antimicrobial activity of TiO2, In: Materials today : proceedings33pp. 2458-2464 Elsevier Ltd

The effect of chalcogens such as sulphur (S), selenium (Se), and tellurium (Te) on the anatase to rutile phase transition (ART) of titanium dioxide (TiO2) was investigated. 2 mol % of chalcogen doped TiO2 was synthesised via a sol–gel technique. The as-synthesised samples were calcined at different temperatures from 500 °C to 800 °C for 2 h. X-ray diffraction (XRD) and Raman spectroscopy were used to study the ART of TiO2. Te -TiO2 showed the highest anatase phase (44%) at 750 °C as compared to other samples. X-ray photoelectron spectroscopy (XPS) and UV–visible diffuse reflectance spectroscopy (UV-DRS) was further utilised to investigate the oxidation state and optical properties. UV-DRS results showed that the substitutional doping of chalcogens in the TiO2 lattice enhanced visible light absorption. The photocatalytic efficiency was tested for the disinfection of Escherichia coli (E.coli) under visible light irradiation. It is noted that while the chalcogen modified TiO2 improved the anatase stability the antimicrobial activity is not significantly enhanced compared to pure anatase TiO2 under visible light illumination. Te-TiO2 attained 100% disinfection within 70 min of visible light irradiation and maintained equal antibacterial efficiency as pure TiO2 at 750 °C.

Vignesh Kumaravel, Stephen Rhatigan, Snehamol Mathew, Marie Clara Michel, John Bartlett, Michael Nolan, Steven J. Hinder, Antonio Gasco, Cesar Ruiz-Palomar, Daphne Hermosilla, Suresh C. Pillai (2020)Mo doped TiO2: impact on oxygen vacancies, anatase phase stability and photocatalytic activity, In: JPhys materials3(2) IOP Publishing Ltd

This work outlines an experimental and theoretical investigation of the effect of molybdenum (Mo) doping on the oxygen vacancy formation and photocatalytic activity of TiO2. Analytical techniques such as x-ray diffraction (XRD), Raman, x-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) were used to probe the anatase to rutile transition (ART), surface features and optical characteristics of Mo doped TiO2 (Mo-TiO2). XRD results showed that the ART was effectively impeded by 2 mol% Mo doping up to 750 degrees C, producing 67% anatase and 33% rutile. Moreover, the crystal growth of TiO2 was affected by Mo doping via its interaction with oxygen vacancies and the Ti-O bond. The formation of Ti-O-Mo and Mo-Ti-O bonds were confirmed by XPS results. Phonon confinement, lattice strain and non-stoichiometric defects were validated through the Raman analysis. DFT results showed that, after substitutional doping of Mo at a Ti site in anatase, the Mo oxidation state is Mo6+ and empty Mo-s states emerge at the titania conduction band minimum. The empty Mo-d states overlap the anatase conduction band in the DOS plot. A large energy cost, comparable to that computed for pristine anatase, is required to reduce Mo-TiO2 through oxygen vacancy formation. Mo5+ and Ti3+ are present after the oxygen vacancy formation and occupied states due to these reduced cations emerge in the energy gap of the titania host. PL studies revealed that the electron-hole recombination process in Mo-TiO2 was exceptionally lower than that of TiO2 anatase and rutile. This was ascribed to introduction of 5s gap states below the CB of TiO2 by the Mo dopant. Moreover, the photo-generated charge carriers could easily be trapped and localised on the TiO2 surface by Mo6+ and Mo5+ ions to improve the photocatalytic activity.

Ciara Byrne, Stephen Rhatigan, Daphne Hermosilla, Noemí Merayo, Ángeles Blanco, Marie Clara Michel, Steven Hinder, Michael Nolan, Suresh C Pillai (2020)Modification of TiO2 with hBN: high temperature anatase phase stabilisation and photocatalytic degradation of 1,4-dioxane, In: Journal of Physics: Materials3(1) IOP Publishing

This paper examines the modification of anatase TiO2 with hexagonal boron nitride (hBN) and the impact this coupling has on the temperature of the anatase to rutile phase transition and photocatalytic activity. All samples were 100% anatase when calcined up to 500 °C. At 600 °C, all BN-modified samples contain mixed rutile and anatase phases, with 8% and 16% BN-TiO2 showing the highest anatase contents of 64.4% and 65.5% respectively. The control sample converted fully to rutile at 600 °C while the BN modified sample converted to rutile only at 650 °C. In addition to TiO2 phase composition, XRD also showed the presence of bulk boron nitride peaks, with the peak at 26° indicating the graphite-like hBN structure. Density functional theory calculations of hBN-rings adsorbed at the anatase (101) surface show strong binding at the interface; new interfacial bonds are formed with key interfacial features being formation of B-O-Ti and N-Ti bonds. Models of extended hBN sheets at the anatase (101) surface show that formation of B-O and N-Ti bonds along the edge of the hBN sheet anchor it to the anatase surface. 16% BN-TiO2 at 500 °C showed a significant increase in the photocatalytic degradation of 1,4-dioxane when compared with pure anatase TiO2 at 500 °C. This arises from the effect of hBN on anatase. The computed density of states (DOS) plots show that interfacing anatase with BN results in a red shift in the TiO2 energy gap; N-p states extend the valence band maximum (VBM) to higher energies. This facilitates transitions from high lying N-p states to the Ti-d conduction band. A simple photoexcited state model shows separation of electrons and holes onto TiO2 and BN, respectively, which promotes the photocatalytic activity.

Ciara Byrne, Saoirse Dervin, Daphne Hermosilla, Noemi Merayo, Angeles Blanco, Steven Hinder, Moussab Harb, Dionysios D. Dionysiou, Suresh C. Pillai (2021)Solar light assisted photocatalytic degradation of 1,4-dioxane using high temperature stable anatase W-TiO2 nanocomposites, In: Catalysis today380pp. 199-208 Elsevier

This work outlines a systematic and detailed study of the modification of anatase TiO2 with tungsten (W). The impact this coupling has on the temperature of the anatase to rutile phase transition and the photocatalytic degradation of 1,4-dioxane, a highly toxic compound that is increasingly present in water bodies is also studied. TiO2 composite photocatalysts with 2, 4, 8 and 16 mol. % W, respectively, were produced using a sol-gel process and then calcined between 500-1000 degrees C. The crystallinity and phase composition of pure and W-TiO2 photocatalysts were examined using X-ray Diffraction (XRD), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). All W-TiO2 composite photocatalysts demonstrated 100 % anatase crystalline phase at calcination temperatures as high as 800 degrees C. Due to the retention of 26 % anatase after calcination at 950 degrees C, 8 mol. % W was established as the optimum W loading for the development of high temperature stable anatase WTiO2 composite photocatalysts. The % anatase content also significantly impacts the photocatalytic activity of the W-TiO2 composite photocatalysts. In the presence of solar light, 100 % of 1,4-dioxane was successfully degraded by 2-W-TiO2, 4-W-TiO2 and 8-W-TiO2 composite photocatalysts, respectively, calcined at 800 degrees C. However, as the calcination temperature increases and the % anatase content decreases, only 70 % of 1,4-dioxane was degraded when using 4-W-TiO2 and 8-W-TiO2 calcined at 900 degrees C. The highest % removal of 1,4-dioxane was also achieved using 8-W-TiO2 calcined at both 800 and 900 degrees C. 8-W-TiO2 is therefore considered the optimum sample for both photocatalysis and phase transition temperature.

M.P. Sooraj, Archana S. Nair, Suresh C. Pillai, Steven J. Hinder, Beena Mathew (2020)CuNPs decorated molecular imprinted polymer on MWCNT for the electrochemical detection of l-DOPA, In: Arabian journal of chemistry13(1)pp. 2483-2495 Elsevier B.V

A novel synthesis of copper nanoparticle (CuNPs) is carried out by the reduction of ethylene diamine Cu complexes using sodiumborohydride as reducing agent. The synthesized copper nanoparticle is grafted with molecular imprinted polymer on MWCNT (CuNPs/MWCNT-MIPs). Fabricated sorbent is used for the molecular recognition and sensing of levodopa (l-DOPA) in human urine and pharmaceutical samples. The non covalent interaction between l-DOPA and the functional groups present in the selective binding sites of the polymer composite sorbent is mainly responsible for the recognition property. The synthesis of CuNPs decorated MWCNT-MIPs and its extents are characterized by employing UV–Vis spectroscopy, Fourier-transform infrared spectroscopy, powder X-ray diffraction analysis, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy techniques. The electrochemical investigation shows that the imprinted (CuNPs/MWCNT-MIP) material has good recognition capacity towards l-DOPA. The sensitivity is found to be directly proportional to the concentration of template with a detection limit of 7.23 × 10−9M (S/N = 3). The specificity and selectivity of the fabricated sensor give a fine discrimination between l-DOPA and structurally related compounds such as dopamine, uric acid, 3,4-Dihydroxyphenylacetic acid and homovanillic acid.

Vijila Kalarivalappil, Steven J. Hinder, Suresh C. Pillai, V. Kumar, Baiju Kizhakkekilikoodayil Vijayan (2018)Stability studies of CdS sensitized TiO2 nanotubes prepared using the SILAR method, In: Journal of environmental chemical engineering6(1)pp. 1404-1413 Elsevier Ltd

[Display omitted] •CdS sensitized titania nanotubes were synthesised by SILAR method.•The stability of CdS upon photocatlytic reaction studied through XPS analysis.•The photoactivity and solar cell efficiency highly depend on the SILAR cycle. Titania nanotubes sensitized with CdS nanoparticles of different sizes and amounts were prepared using the successive ionic layer (SILAR) deposition method. UV/visible spectra indicate a red shift in CdS absorption upon increasing the number of SILAR cycles this is due to an increase in amount and size of CdS particles on the surface of titania nanotube. The stability of CdS particle sensitized on the surface of titania nanotubes were monitored using X-ray photoelectron spectroscopy (XPS). The formation of CdSO4 species on the surface of CdS particles was evident from the XPS analysis. Smaller CdS particles, formed using a lower number of SILAR cycles, are more prone to oxidation than the larger particles formed using a greater number of SILAR cycles. The photocatalytic activity and solar cell efficiency is found to be dependent on the number of SILAR cycles employed.

Thomas Abraham, K. R. Rejil, Jaise Mariya George, Arun Antony, Suresh C. Pillai, Steven J. Hinder, Beena Mathew (2020)Magnetic Fe3O4-reduced graphene oxide composite decorated with Ag nanoparticles as electrochemical sensor and self-cleaning material for organic pollutants, In: Journal of porous materials27(1)pp. 303-318 Springer Nature

The successful synthesis of silver incorporated Fe3O4-rGO ternary nanocomposite for the accurate detection of toxic phenolic isomeric compounds by electrochemical sensing along with self-cleaning ability of photo degradation of the organic dirts is described in this paper. The salient feature of this work is the high sensitivity of the synthesized sensor up to the nanomolar level. The detection limit of the phenolic isomeric compounds such as hydroquinone and catechol are found to be 37.5 nM and 335.4 nM respectively. The synthesized nanohybrid possessing large surface area and mesoporosity also aims to the effective photodegradation of various industrial acidic and basic dyes which may impair electrochemical sensing nature. The photo degradation capacity of the ternary composite was studied and found that a high reduction percentage of above 95 is obtained for these toxic industrial dyes. The dual applications of the ternary nanohybrid as an efficient electrochemical sensor with better photocatalytic self-cleaning property opened a new platform in the various analytical and industrial fields.

Anastasios I. Tsiotsias, Nikolaos D. Charisiou, Eleana Harkou, Sanaa Hafeez, George Manos, Achilleas Constantinou, Aseel G.S. Hussien, Aasif A. Dabbawala, Victor Sebastian, Steven J. Hinder, Mark A. Baker, Kyriaki Polychronopoulou, Maria A. Goula (2022)Enhancing CO2 methanation over Ni catalysts supported on sol-gel derived Pr2O3-CeO2: An experimental and theoretical investigation, In: Applied catalysis. B, Environmental318 Elsevier B.V

Ni-based catalysts supported on sol-gel prepared Pr-doped CeO2 with varied porosity and nanostructure were tested for the CO2 methanation reaction. It was found that the use of ethylene glycol in the absence of H2O during a modified Pechini synthesis led to a metal oxide support with larger pore size and volume, which was conducive toward the deposition of medium-sized Ni nanoparticles confined into the nanoporous structure. The high Ni dispersion and availability of surface defects and basic sites acted to greatly improve the catalyst’s activity. CFD simulations were used to theoretically predict the catalytic performance given the reactor geometry, whereas COMSOL and ASPEN software were employed to design the models. Both modelling approaches (CFD and process simulation) showed a good validation with the experimental results and therefore confirm their ability for applications related to the prediction of the CO2 methanation behaviour. [Display omitted] •Variation of sol-gel synthesis can alter the Pr-doped CeO2 support nanostructure.•Modified Pechini synthesis enhances the metal oxide porosity and pore volume.•Higher pore size and volume leads to medium-sized supported Ni nanoparticles.•Improved Ni dispersion, defect chemistry and basicity promote CO2 methanation.•CFD successfully predicts the catalysts’ performance and the reactor species.

Ciara Byrne, Lorraine Moran, Daphne Hermosilla, Noemí Merayo, Ángeles Blanco, Stephen Rhatigan, Steven Hinder, Priyanka Ganguly, Michael Nolan, Suresh C. Pillai (2019)Effect of Cu doping on the anatase-to-rutile phase transition in TiO2 photocatalysts: Theory and experiments, In: Applied catalysis. B, Environmental246pp. 266-276 Elsevier B.V

[Display omitted] •Samples of different mol% of copper doped titania were studied.•At 650 °C, samples with 0% and 2% Cu were comprised of 100% rutile.•4% and 8% Cu doping the samples showed 27.3% and 74.3% anatase respectively.•DFT studies of show formation of oxygen vacancies and a 2+ oxidation state for Cu. This paper shows that incorporation of Cu inhibits the anatase to rutile phase transition at temperatures above 500 °C. The control sample, with 0% Cu contained 34.3% anatase at 600 °C and transitioned to 100% rutile by 650 °C. All copper doped samples maintained 100% anatase up to 600 °C. With 2% Cu doping, anatase fully transformed to rutile at 650 °C, at higher Cu contents of 4% & 8% mixed phased samples, with 27.3% anatase and 74.3% anatase respectively, are present at 650 °C. All samples had fully transformed to rutile by 700 °C. 0%, 4% and 8% Cu were evaluated for photocatalytic degradation of 1, 4 dioxane. Without any catalyst, 15.8% of the 1,4 dioxane degraded upon irradiation with light for 4 h. Cu doped TiO2 shows poor photocatalytic degradation ability compared to the control samples. Density functional theory (DFT) studies of Cu-doped rutile and anatase show formation of charge compensating oxygen vacancies and a Cu2+ oxidation state. Reduction of Cu2+ to Cu+ and Ti4+ to Ti3+ was detected by XPS after being calcined to 650–700 °C. This reduction was also shown in DFT studies. Cu 3d states are present in the valence to conduction band energy gap upon doping. We suggest that the poor photocatalytic activity of Cu-doped TiO2, despite the high anatase content, arises from the charge recombination at defect sites that result from incorporation of copper into TiO2.

Vignesh Kumaravel, Stephen Rhatigan, Snehamol Mathew, John Bartlett, Michael Nolan, Steven J. Hinder, Preetam K. Sharma, Anukriti Singh, J. Anthony Byrne, John Harrison, Suresh C. Pillai (2019)Indium-Doped TiO2 Photocatalysts with High-Temperature Anatase Stability, In: Journal of physical chemistry. C123(34)pp. 21083-21096 Amer Chemical Soc

The thermal stability of anatase titanium dioxide (TiO2) is a prerequisite to fabricate photocatalyst-coated indoor building materials for use in antimicrobial and self-cleaning applications under normal room light illumination. Metal doping of TiO2 is an appropriate way to control the anatase to rutile phase transition (ART) at high processing temperatures. In this work, ART of indium (In)-doped TiO2 (In-TiO2) was investigated in detail in the range of 500-900 degrees C. In-TiO2 (In mol % = 0-16) was synthesized via a modified sol-gel approach. These nanoparticles were further characterized by means of powder X-ray diffraction (XRD), Raman, photoluminescence (PL), transient photocurrent response, and X-ray photoelectron spectroscopy (XPS) techniques. XRD results showed that the anatase phase was maintained up to 64% by 16 mol % of In doping at 800 degrees C of calcination temperature. XPS results revealed that the binding energies of (Ti 2p(1/2 )and Ti 2p(3/2)) were red-shifted by In doping. The influence of In doping on the electronic structure and oxygen vacancy formation of anatase TiO2 was studied using density functional theory corrected for on-site Coulomb interactions (DFT+U). First-principles results showed that the charge-compensating oxygen vacancies form spontaneously at sites adjacent to the In dopant. DFT+U calculations revealed the formation of In - Ss states in the band gap of the anatase host. The formation of In2O3 at the anatase surface was also examined using a slab model of the anatase (101) surface modified with a nanocluster of composition In4O6. The formation of a reducing oxygen vacancy also has a moderate energy cost and results in charge localization at In ions of the supported nanocluster. PL and photocurrent measurements suggested that the charge carrier recombination process in TiO2 was reduced in the presence of In dopant. The photocatalytic activity of 2% In-TiO2 calcined at 700 degrees C is more comparable with that of pure anatase.

M.O. King, M.T. Staff, A.L. White, M. Kopec, M. Stapleton, S.J. Hinder, J.F. Watts (2021)UV fluorescence as a method of high throughput surface cleanliness assessment: A comparison with XPS, In: International journal of adhesion and adhesives104 Elsevier Ltd

UV visible fluorescence (UV–vis) was trialled as a method for the rapid screening of surface cleanliness of metals. By comparing the relative intensity of the fluorescence to the film thickness of the carbonaceous contamination, an evaluation of the effectiveness of UV–vis was made. Surface composition and the thickness of carbon contamination on stainless steel/mineral oil and copper/tallow wax samples was measured with X-ray photoelectron spectroscopy (XPS). After vapour degreasing with trichloroethylene it was found that residual tallow wax was not effectively detected by UV–vis; whereas a commercial mineral oil was readily detected by UV–vis. The reason for the lack of fluorescence is that the tallow wax is largely an unconjugated system, in that it mostly comprises saturated or monounsaturated carbon – carbon bonds, which do not fluoresce. Using imaging XPS an increase in carbon film thickness close to the edge of the sample is observed, a result of solvent residue caused by the interfacial tension that exists between the solvent and the substrate. UK Ministry of Defence © Crown Owned Copyright 2020/AWE.

Roba Saab, Kyriaki Polychronopoulou, Dalaver H. Anjum, Nikolaos D. Charisiou, Maria A. Goula, Steven J. Hinder, Mark A. Baker, Andreas Schiffer (2022)Effect of SiO2/Al2O3 ratio in Ni/Zeolite-Y and Ni-W/Zeolite-Y catalysts on hydrocracking of heptane, In: Molecular catalysis528 Elsevier

This study investigated the effect of the SiO2/Al2O3 ratio in the range of 5-80 in zeolite Y (ZY) as a support for the bi-functional reaction of heptane hydrocracking. Bi-metallicity impact, through the addition of W on Ni in the supported metal catalysts was also examined. The catalytic activity was assessed at 350?C and 400?C in order to deduce an optimized composition of the catalyst in terms of metal composition and Si/Al ratio. The results were correlated to the catalysts' surface and bulk properties, the latter after employing a number of material characterization techniques. It was shown that Ni-W bimetallic catalysts demonstrated better catalytic activity (conversion, 78% to 91%) than Ni-based monometallic counterpart catalysts (conversion, 74.2% to 82.7%), with NiO-WO3-ZY30 (SiO2/Al2O3 ratio equal to 30) exhibiting the highest conversion. This was attributed to the bimetallic's enhanced metal dispersion and smaller particle size, evaluated using temperature-programmed desorption (TPD) of H-2 and high-resolution transmission electron microscopy (HR-TEM) imaging. The stronger acidity, as quantified by total acidity calculations, of zeolite Y having higher Si/Al ratio, and their balanced ratio of micro-and meso-porosity played a vital role in their catalytic performance. This study provides useful design guidelines on how to adjust both the Si/Al ratio in the zeolite Y support and the catalyst's bimetallicity for enhanced hydrocracking performance.

Vignesh Kumaravel, Maria Barbara Maccioni, Snehamol Mathew, Steven J Hinder, John Bartlett, Michael Nolan, Suresh C Pillai (2022)Unravelling the Impact of Ta Doping on the Electronic and Structural Properties of Titania: A Combined Theoretical and Experimental Approach, In: Journal of physical chemistry. C126(4)pp. 2285-2297 American Chemical Society

The introduction of new energy levels in the forbidden band through the doping of metal ions is an effective strategy to improve the thermal stability of TiO2. In the present study, the impact of Ta doping on the anatase to rutile transition, structural characteristics, and anion and cation vacancy formation were investigated in detail using density functional theory and experimental characterization, including X-ray diffraction, Raman, Brunauer–Emmett–Teller surface area, UV–vis diffuse reflectance spectroscopy, high-resolution transmission electron spectroscopy, and X-ray photoelectron spectroscopy. The average crystallite size of TiO2 decreases with an increase in the Ta concentration. At high temperatures, more oxygen atoms enter the crystal lattice and occupy the vacancies, leading to lattice expansion. Importantly, we find that Ta doping preserved the anatase content of TiO2 up to annealing temperatures of 850 °C which allows anatase stability to be maintained at typical ceramic processing temperatures. The substitution of Ti4+ by the Ta5+ ions increased the electron concentration in the crystal lattice through formation of Ti3+ defect states. Raman studies revealed the formation of new Ta bonds via disturbing the Ti–O–Ti bonds in the crystal lattice. It is concluded that under the oxidizing conditions the Ta5+ ions could be enhanced on the Ta–TiO2 surface due to slow diffusion kinetics.

Hassan Wahab, Mohamed M. El Gomati, Steven J. Hinder, John F. Watts (2018)A growth mechanism for carbon nanotubes using metal oxides as catalysts, In: Surface and interface analysis50(7)pp. 734-743 Wiley

Metal oxides have only recently begun to be used as catalysts for the growth of carbon nanotubes. Here, we propose a new model for the growth of carbon nanotubes, based on the intra-granular charge transfer transition and the lattice strain of the catalyst nanoparticles. This is supported by results obtained from the doped metal oxides like samarium doped zinc oxide (SmZnO) and terbium doped zinc oxide (TbZnO). The intragranular charge transfer transition is believed to be responsible for the dissociation of the hydrocarbon molecules. The lattice strain of the catalyst nanoparticles appears to be responsible for the diffusion of carbon atoms through the catalyst particles.

Abdulaziz H. Alanazi, Izabela Jurewicz, Amjad Alyahyawi, Abdullah Alsubaie, Steven Hinder, Jorge Banuls-Ciscar, Mohammed Alkhorayef, J. F. Watts, D. A. Bradley (2019)Novel dosimetric study of the sp(2) to sp(3) hybridisation ratio in free-standing carbon nanotubes buckypaper, In: Radiation physics and chemistry (Oxford, England : 1993)154pp. 38-45 Elsevier

Over the past several years a great deal of research has focused on the adaptation of carbon nanotubes (CNTs) for a wide range of applications, including as gas detectors, in energy storage, for various photonics purposes, also as radiation sensors. In previous studies by this group, investigating thermoluminescent (TL) properties, the sensitivity of CNTs towards ionising radiations has been observed using beta radiation at dose levels from fractions of a Gy and more. Strain and impurity defects in CNTs give rise to substantial TL yields, the extent to which electron trapping centres exist varying inversely with the quality of CNT, from super-pure to pure to raw. In present study the contribution to TL of beta particle irradiated CNTs has been investigated with respect to changes in the lattice atomic orbitals, pointing to the possibility of a new radiation dosimetry method. The surface-sensitive method, one highly suited to the thin (few tens of pm thick) CNT samples produced in the form of free-standing buckypaper, is based on use of the X-Ray Photoelectron Spectroscopy (XPS) technique, evaluating sp(2) to sp(3) hybridisation. The CNT samples have been examined subsequent to irradiation using a relatively large activity Sr-90/Y-90 radionuclide source (E-beta = 0.546 MeV/2.28 MeV), delivering doses in the range 0.2-6 Gy, in all three qualities sp(2) to sp(3) hybridisation being observed to increase with dose deposition. Considerable advantage is seen in making use of such thin CNTs in dosimetry, rendering them particularly suitable for beta particle soft tissue dosimetry.

Wenliang Feng, Venkata Sai Avvaru, Steven J. Hinder, Vinodkumar Etacheri (2022)High-energy sodium-ion hybrid capacitors through nanograin-boundary-induced pseudocapacitance of Co3O4 nanorods, In: Journal of energy chemistry69pp. 338-346 Elsevier B.V

A high energy density (175 Wh/kg) sodium-ion hybrid capacitor based on nanograin-boundary-rich hierarchical Co3O4 nanorod anode is reported. Outstanding electrochemical performance is credited to the enhanced pseudocapacitive sodium-ion storage resulting from nanograin-boundaries. [Display omitted] Sodium-ion hybrid capacitors (SICs) have been proposed to bridge performance gaps between batteries and supercapacitors, and thus realize both high energy density and power density in a single configuration. Nevertheless, applications of SICs are severely restricted by their insufficient energy densities (

Andrius Subacius, Bill Baloukas, Etienne Bousser, Steve J. Hinder, Mark A. Baker, Claus Rebholz, Allan Matthews (2020)Nanostructural Characterisation and Optical Properties of Sputter-Deposited Thick Indium Tin Oxide (ITO) Coatings, In: Coatings (Basel)10(11)pp. 1-7 Mdpi

Indium tin oxide (ITO) thin films, used in many optoelectronic applications, are typically grown to a thickness of a maximum of a few hundred nanometres. In this work, the composition, microstructure and optical/electrical properties of thick ITO coatings deposited by radio frequency magnetron sputtering from a ceramic ITO target in an Ar/O-2 gas mixture (total O-2 flow of 1%) on unheated glass substrates are reported for the first time. In contrast to the commonly observed (200) or (400) preferential orientations in ITO thin films, the approximately 3.3 mu m thick coatings display a (622) preferential orientation. The ITO coatings exhibit a purely nanocrystalline structure and show good electrical and optical properties, such as an electrical resistivity of 1.3 x 10(-1) Omega center dot cm, optical transmittance at 550 nm of similar to 60% and optical band gap of 2.9 eV. The initial results presented here are expected to provide useful information for future studies on the synthesis of high-quality thick ITO coatings.

Kyriaki Polychronopoulou, Nikolaos D. Charisiou, Georgios I. Siakavelas, Ayesha A. AlKhoori, Victor Sebastian, Steven J. Hinder, Mark A. Baker, Maria A. Goula (2019)Ce-Sm-xCu cost-efficient catalysts for H-2 production through the glycerol steam reforming reaction, In: Sustainable energy & fuels3(3)pp. 673-691 Royal Soc Chemistry

A series of Ce-Sm-xCu (x = 5, 7, and 10 at%) catalysts were prepared through coupling of microwave irradiation with a sol-gel method and were evaluated for the glycerol steam reforming reaction in the 400-750 degrees C temperature range. Some critical comparison with co-precipitation catalysts is also discussed. The catalysts were characterized using BET, Raman, XRD, NH3-TPD, CO2-TPD, H-2-TPR, SEM, HAADF-STEM and XPS analyses, while the bonding environment and thermal stability of the catalyst precursor compounds were studied using FTIR and TGA/ DSC. For all catalysts it was found that the Ce, Sm, and Cu cations are all homogeneously distributed in the cubic fluorite cell with interplanar spacings of 0.355 nm, 0.370 nm and 0.373 nm for the Ce-Sm-5Cu, Ce-Sm-7Cu and Ce-Sm-10Cu catalysts, respectively. The surface of the catalysts was found to be Ce-and Cu-poor and Sm-rich, with Ce4+, Ce3+, Sm3+, Cu2+ and Cu+ oxidation states identified. In the bulk, the oxygen vacancies were found to be dependent on the catalyst composition (Cu content). Among the catalysts studied, the Ce-Sm-5Cu one exhibits the highest selectivity for hydrogen (H2) with its SH2 ranging from 40% (400 degrees C) to 75% (750 degrees C). The Ce-Sm-5Cu catalyst also produces the highest amount of CO (97-71%) and the lowest amount of CO2 (3-28%) among all samples for the low reaction temperature range (400 degrees C < T < 600 degrees C). For all catalysts, the CO/ CO2 molar ratio is quite low (< 7.0) in the whole temperature range, while the H-2/CO molar ratio value remains almost stable (similar to 2.0) for 400 degrees C < T < 600 degrees C; it increases sharply for T > 650 degrees C and reaches values of 7, 10 and 12 for the samples Ce-Sm-5Cu, Ce-Sm-7Cu, and Ce-Sm10Cu, respectively. All the catalysts showed a glycerol conversion of 80% after 6 h time on stream, although a variety of coke species was found on their surfaces. A potential correlation between Cu content and coke deposition was attempted.

C. Costa, M. Jang, J. de Jesus, R. T. Steven, C. J. Nikula, E. Elia, J. Bunch, A. T. Bellew, J. F. Watts, S. Hinder, M. J. Bailey (2021)Imaging mass spectrometry: a new way to distinguish dermal contact from administration of cocaine, using a single fingerprint, In: Analyst (London)146(12)pp. 4010-4021

Here we show a new and significant application area for mass spectrometry imaging. The potential for fingerprints to reveal drug use has been widely reported, with potential applications in forensics and workplace drug testing. However, one unsolved issue is the inability to distinguish between drug administration and contamination by contact. Previous work using bulk mass spectrometry analysis has shown that this distinction can only be definitively made if the hands are washed prior to sample collection. Here, we illustrate how three mass spectrometry imaging approaches, desorption electrospray ionisation (DESI), matrix assisted laser desorption ionisation (MALDI) and time of flight secondary ion mass spectrometry (ToF-SIMS) can be used to visualise fingerprints at different pixel sizes, ranging from the whole fingerprint down to the pore structure. We show how each of these magnification scales can be used to distinguish between cocaine use and contact. We also demonstrate the first application of water cluster SIMS to a fingerprint sample, which was the sole method tested here that was capable of detecting excreted drug metabolites in fingerprints, while providing spatial resolution sufficient to resolve individual pore structure. We show that after administration of cocaine, lipids and salts in the fingerprint ridges spatially correlate with the cocaine metabolite, benzoylecgonine. In contrast after contact, we have observed that cocaine and its metabolite show a poor spatial correlation with the flow of the ridges.

Vignesh Kumaravel, Enrico Bianchetti, Snehamol Mathew, Steven J Hinder, John Bartlett, Cristiana Di Valentin, Suresh C Pillai (2021)New Insights into Crystal Defects, Oxygen Vacancies, and Phase Transition of Ir-TiO2, In: Journal of physical chemistry. C125(42)pp. 23548-23560 American Chemical Society

The impact of iridium (Ir) doping on the oxygen vacancies, relative stability, crystallite size, surface area, and anatase-to-rutile transition of TiO2 was comprehensively investigated in this study. Ir-doped TiO2 (Ir-TiO2) was synthesized through a sol–gel technique, and the samples were annealed in the temperature range of 400–700 °C. Density functional theory calculations showed that the energy cost of an oxygen vacancy formation for Ir-TiO2 was lower, as compared to that of the pristine TiO2, with the formation of Ir3+ states in the band gap. Ir could provide more rutile nucleation sites and accelerate the rutile formation through the crystal strain relaxation. The entropy of mixing was reduced by the incorporation of Ir, which could induce the rutile formation with an increase in Gibbs free energy at temperatures below the normal phase transition temperature for pure TiO2. The rutile formation of Ir-TiO2 could take place at a low annealing temperature (400 °C) compared to pristine TiO2 (600 °C), indicating that the activation energy for phase transition could be decreased by incorporating Ir. XPS revealed the spin–orbit coupling of Ir 4f peaks, Ir 4f7/2 (61.96 eV) and Ir 4f5/2 (64.77 eV), due to the presence of Ir3+. Raman studies indicated the formation of charge-compensating oxygen vacancies and the presence of d states by Ir doping. It is concluded that the defects originated because the incorporation of Ir could facilitate rutile nucleation sites and thereby accelerate the phase transition through strain relaxation.

Mark A. Hughes, Alexander Burgess, Steven Hinder, A. Baset Gholizadeh, Christopher Craig, Daniel W. Hewak (2018)High speed chalcogenide glass electrochemical metallization cells with various active metals, In: Nanotechnology29(31)pp. 315202-315202 Iop Publishing Ltd

We fabricated electrochemical metallization cells using a GaLaSO solid electrolyte, an InSnO inactive electrode and active electrodes consisting of various metals (Cu, Ag, Fe, Cu, Mo, Al). Devices with Ag and Cu active metals showed consistent and repeatable resistive switching behaviour, and had a retention of 3 and >43 days, respectively; both had switching speeds of

Georgios I. Siakavelas, Nikolaos D. Charisiou, Ayesha AlKhoori, Safa Gaber, Victor Sebastian, Steven J. Hinder, Mark A. Baker, Ioannis V. Yentekakis, Kyriaki Polychronopoulou, Maria A. Goula (2022)Oxidative coupling of methane on Li/CeO2 based catalysts: Investigation of the effect of Mg- and La-doping of the CeO2 support, In: Molecular catalysis520 Elsevier B.V

•Li+ ions caused oxygen vacancy sites and the formation of O22− and O2– species.•Surface basicity and electrophilic oxygen sites control the OCM activity.•Low concentration of Li changed the reaction pathway and products’ distribution.•The electrophilic oxygen species improved the OCM activity and selectivity.•Li/Mg-Ce showed the higher production of C2H4 due to its basicity and oxygen sites. The work presented herein reports on the oxidative coupling of methane (OCM) performance of a series of Li-free and Li-doped CeO2 and CeO2 modified with Mg2+ and La3+ catalysts. The supporting materials (Ce, Mg-Ce and La-Mg-Ce metal oxides) were synthesized using the microwave assisted sol-gel method, while lithium ions were added using the wet impregnation technique, to further affect the physicochemical properties, activity and selectivity of the materials, in terms of the desirable hydrocarbon products (C2H4 and C2H6). The materials were characterized towards their textural, structural and redox properties, surface basicity, and surface morphology using N2 adsorption/desorption, X-Ray Diffraction (XRD), Raman spectroscopy, CO2-Temperature Programmed Desorption (CO2-TPD), H2-Temperature Programmed Reduction (H2-TPR), Scanning Electron Microscopy (SEM), and X-ray Photoelectron Spectroscopy (XPS). Catalytic activity was assessed between 600 and 870 °C, at atmospheric pressure and different CH4:O2 molar ratios and Weigh-basis Gas Hourly Space Velocity (WGHSV). It is concluded that low specific surface area values, the existence of surface moderate basic sites, increased concentration of oxygen vacancies and the presence of electrophilic oxygen species (O2– and O22–) on the catalyst surface had a crucial role on the improvement of the catalytic performance in terms of the desirable products, mainly ethylene. It is noted that the addition of Li changed thoroughly the reaction pathway and the products’ distribution, with the C2 selectivity values exceeding 85%. The Li/Mg-Ce catalyst, presenting the higher population of intermediate basic sites and surface superoxide species, showed an improved catalytic activity in terms of XCH4 and production of ethylene, while the incorporation of La3+ into the crystal structure of CeO2 suppressed the production of ethylene. Finally, smaller CH4:O2 molar ratios suppressed the production of hydrocarbons, while enhanced residence times, favoured the dehydrogenation of C2H6 to C2H4. [Display omitted] .

Nikolaos D. Charisiou, Victor Sebastian, Steven J. Hinder, Mark A. Baker, Kyriaki Polychronopoulou, Maria A. Goula (2019)Ni Catalysts Based on Attapulgite for Hydrogen Production through the Glycerol Steam Reforming Reaction, In: Catalysts9(8) Mdpi

Attapulgite (ATP, a natural clay) was used as carrier to produce a nickel-based catalyst (Ni/ATP) for the work that is presented herein. Its catalytic performance was comparatively assessed with a standard Ni/Al2O3 sample for the glycerol steam reforming (GSR) reaction. It was shown that the ATP support led to lower mean Ni crystallite size, i.e., it increased the dispersion of the active phase, to the easier reduction of NiO and also increased the basicity of the catalytic material. It was also shown that it had a significant effect on the distribution of the gaseous products. Specifically, for the Ni/ATP catalyst, the production of liquid effluents was minimal and subsequently, conversion of glycerol into gaseous products was higher. Importantly, the Ni/ATP favored the conversion into H-2 and CO2 to the detriment of CO and CH4. The stability experiments, which were undertaken at a low WGFR, showed that the activity of both catalysts was affected with time as a result of carbon deposition and/or metal particle sintering. An examination of the spent catalysts revealed that the coke deposits consisted of filamentous carbon, a type that is known to encapsulate the active phase with fatal consequences.

Roba Saab, Kyriaki Polychronopoulou, Dalaver H. Anjum, Nikolaos Charisiou, Maria A. Goula, Steven J. Hinder, Mark A. Baker, Andreas Schiffer (2022)Carbon Nanostructure/Zeolite Y Composites as Supports for Monometallic and Bimetallic Hydrocracking Catalysts, In: Nanomaterials (Basel, Switzerland)12(18) Mdpi

In this study, we examine the effect of integrating different carbon nanostructures (carbon nanotubes, CNTs, graphene nanoplatelets, GNPs) into Ni- and Ni-W-based bi-functional catalysts for hydrocracking of heptane performed at 400 degrees C. The effect of varying the SiO2/Al2O3 ratio of the zeolite Y support (between 5 and 30) on the heptane conversion is also studied. The results show that the activity, in terms of heptane conversion, followed the order CNT/Ni-ZY5 (92%) > GNP/Ni-ZY5 (89%) > CNT/Ni-W-ZY30 (86%) > GNP/Ni-W-ZY30 (85%) > CNT/Ni-ZY30 (84%) > GNP/Ni-ZY30 (83%). Thus, the CNT-based catalysts exhibited slightly higher heptane conversion as compared to the GNP-based ones. Furthermore, bimetallic (Ni-W) catalysts possessed higher BET surface areas (725 m(2)/g for CNT/Ni-W-ZY30 and 612 m(2)/g for CNT/Ni-ZY30) and exhibited enhanced hydrocracking activity as compared to the monometallic (Ni) catalyst with the same zeolite support and type of carbon structure. It was also shown that CNT-based catalysts possessed higher regeneration capability than their GNP-based counterparts due to the slightly higher thermal stability of the CVD-grown CNTs.

Jamie J. Grant, Suresh C. Pillai, Tatiana S. Perova, Sarah Hehir, Steven J. Hinder, Marion McAfee, Ailish Breen (2021)Electrospun Fibres of Chitosan/PVP for the Effective Chemotherapeutic Drug Delivery of 5-Fluorouracil, In: Chemosensors9(4) Mdpi

Electrospun nanofibrous mats consisting of chitosan (CS) and polyvinylpyrrolidone (PVP) were constructed. Tuning of solution and process parameters was performed and resulted in an electrospun system containing a 6:4 ratio of PVP:CS. This is a significant increase in the proportion of spun CS on the previously reported highest ratio PVP:CS blend. SEM analysis showed that the nanofibrous mats with 4 wt% CS/6 wt% PVP (sample E) comprised homogenous, uniform fibres with an average diameter of 0.569 mu m. XPS analysis showed that the surface of the samples consisted of PVP. Raman and FTIR analysis revealed intermolecular interactions (via H-bonding) between PVP and CS. In FTIR spectra, the contribution of chitosan to CS/PVP complexes was shown by the downshift of the C=O band and by the linear increase in intensity of C-O stretching in CS. XPS analysis showed a smaller shift at the binding energy 531 eV, which relates to the amide of the acetylated functional groups. The obtained results demonstrate a sensitivity of Raman and FTIR tests to the presence of chitosan in PVP:CS blend. The chemotherapy drug 5-Fu was incorporated into the constructs and cell viability studies were performed. WST-8 viability assay showed that exposure of A549 human alveolar basal epithelial cells to 10 mg/mL 5-Fu loaded fibres was most effective at killing cells over 24 h. On the other hand, the constructs with loading of 1 mg/mL of drug were not efficient at killing A549 human alveolar basal epithelial cells. This study showed that CS/PVP/5-Fu constructs have potential in chemotherapeutic drug delivery systems.

Maitha AlKetbi, Kyriaki Polychronopoulou, Maguy Abi Jaoude, Michalis A. Vasiliades, Victor Sebastian, Steven J. Hinder, Mark A. Baker, Abdallah F. Zedan, Angelos M. Efstathiou (2020)Cu-Ce-La-O-x as efficient CO oxidation catalysts: Effect of Cu content, In: Applied surface science505 Elsevier

w Nanograins of Ce-La-xCu-O mixed metal oxides (where x = 3, 5, 7, 10, 20 at.%), of approximately 16 nm(2) area size, and having all the metal cations homogeneously distributed, are tested as ternary catalytic materials towards the CO oxidation in the 100-475 degrees C range. Preservation of the cubic ceria lattice structure in those catalysts following La3+ (heavy) and Cu2+ (light) metal cations doping is confirmed based on the powder X-ray diffraction and Raman shift studies. From X-ray photoelectron spectroscopy studies, the presence of mixed Ce3+/Ce4+ and Cu2+/Cu1+ oxidation states was confirmed, which was more profound in the low Cu-content Ce-La-xCu-O catalysts. The copper doping is also found to increase the concentration of oxygen vacant sites in the doped-CeO2 solid as demonstrated from the increase of the Raman intensity ratio I-Ov/I-F2g, of 1.58 and 1.78 with the increase in copper content from 7 to 20 at.% as compared to the lower value of 0.44 obtained for the Cu-free catalyst (Ce-La). The mobility of the surface and bulk oxygen ions in the lattice of such doped-CeO2 materials is further investigated using O-16/O-18 transient isothermal isotopic exchange (TIIE) experiments, and is found to be Cu at.% dependent. For the case of Ce-La-20Cu, the participation of the lattice oxygen (O-L) in the reaction mechanism has been demonstrated using transient experiments. Accordingly, the specific rate (mu mol CO m(-2)s(-1)) of the CO oxidation reaction is found to be higher for the Ce-La-20Cu and Ce-La-7Cu catalysts, corroborating thus the presence of more mobile/labile oxygen species in those ternary catalysts as opposed to the other lower copper compositions.

Snehamol Mathew, Priyanka Ganguly, Stephen Rhatigan, Vignesh Kumaravel, Ciara Byrne, Steven J. Hinder, John Bartlett, Michael Nolan, Suresh C. Pillai (2018)Cu-Doped TiO2: Visible Light Assisted Photocatalytic Antimicrobial Activity, In: Applied sciences8(11) Mdpi

Surface contamination by microbes is a major public health concern. A damp environment is one of potential sources for microbe proliferation. Smart photocatalytic coatings on building surfaces using semiconductors like titania (TiO2) can effectively curb this growing threat. Metal-doped titania in anatase phase has been proven as a promising candidate for energy and environmental applications. In this present work, the antimicrobial efficacy of copper (Cu)-doped TiO2 (Cu-TiO2) was evaluated against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) under visible light irradiation. Doping of a minute fraction of Cu (0.5 mol %) in TiO2 was carried out via sol-gel technique. Cu-TiO2 further calcined at various temperatures (in the range of 500-700 degrees C) to evaluate the thermal stability of TiO2 anatase phase. The physico-chemical properties of the samples were characterized through X-ray diffraction (XRD), Raman spectroscopy, X-ray photo-electron spectroscopy (XPS) and UV-visible spectroscopy techniques. XRD results revealed that the anatase phase of TiO2 was maintained well, up to 650 degrees C, by the Cu dopant. UV-vis results suggested that the visible light absorption property of Cu-TiO2 was enhanced and the band gap is reduced to 2.8 eV. Density functional theory (DFT) studies emphasize the introduction of Cu+ and Cu2+ ions by replacing Ti4+ ions in the TiO2 lattice, creating oxygen vacancies. These further promoted the photocatalytic efficiency. A significantly high bacterial inactivation (99.9999%) was attained in 30 min of visible light irradiation by Cu-TiO2.

Anastasios I. Tsiotsias, Nikolaos D. Charisiou, Ayesha AlKhoori, Safa Gaber, Vlad Stolojan, Victor Sebastian, Bart van der Linden, Atul Bansode, Steven J. Hinder, Mark A. Baker, Kyriaki Polychronopoulou, Maria A. Goula (2022)Optimizing the oxide support composition in Pr-doped CeO2 towards highly active and selective Ni-based CO2 methanation catalysts, In: Journal of energy chemistry71pp. 547-561 Elsevier B.V

Pr doping of CeO2 up to 10at% (Ce0.9Pr0.1O2-δ) in Ni/CeO2 increases the oxygen vacancy population and reduces the Ni particle size, improving CO2 methanation activity and lowering the activation energy. [Display omitted] In this study, Ni catalysts supported on Pr-doped CeO2 are studied for the CO2 methanation reaction and the effect of Pr doping on the physicochemical properties and the catalytic performance is thoroughly evaluated. It is shown, that Pr3+ ions can substitute Ce4+ ones in the support lattice, thereby introducing a high population of oxygen vacancies, which act as active sites for CO2 chemisorption. Pr doping can also act to reduce the crystallite size of metallic Ni, thus promoting the active metal dispersion. Catalytic performance evaluation evidences the promoting effect of low Pr loadings (5 at% and 10 at%) towards a higher catalytic activity and lower CO2 activation energy. On the other hand, higher Pr contents negate the positive effects on the catalytic activity by decreasing the oxygen vacancy population, thereby creating a volcano-type trend towards an optimum amount of aliovalent substitution.

B.C. Bussell, PN Gibson, JOSEPH DANIEL LAWTON, PIERRE COUTURE, M.K. Sharpe, J. England, STEVEN JOHN HINDER, VLAD STOLOJAN, S.A. Thornley, MARK ALAN BAKER (2022)The effect of RF plasma power on remote plasma sputtered AZO thin films, In: Surface and Coatings Technology Elsevier

Aluminium-doped ZnO (AZO) thin films were deposited by remote plasma sputtering of a ZnO:Al2O3 98:2 wt.% ceramic target in a pulsed DC configuration. The target power was kept constant at 445 W and the RF plasma power was varied between 0.5 and 2.5 kW. The as-deposited AZO thin films exhibited an optimum resistivity of 6.35 x 10-4 .cm and optical transmittance of 92 % at a RF plasma power 1.5 kW. The thin film microstructure, chemical composition, and residual stress were investigated using SEM, RBS, XPS and XRD. Accurate determination of the chemical composition and correct interpretation of GIXRD data for AZO thin films are a particular focus of this work. The AZO layer thickness was 500 - 700 nm and Al content in the range of 2.3 - 3.0 at.%, determined by RBS. The AZO thin films exhibited a strong (002) preferential orientation and grain sizes between 70 and 110 nm. The (103) peak intensity enhancement in GIXRD is proven to be a result of the strong (002) preferential orientation and GIXRD geometrical configuration rather than a change in the crystallite orientation at the surface. XPS depth profiles show preferential sputtering of O and Al using a 500 eV Ar+ beam, which can be reduced, but not eradicated using an 8 keV Ar150+ beam. The preferential sputtering can be successfully modelled using the simulation software TRIDYN. A plasma power of 1.5 kW corresponds to a highly ionised plasma and various microstructural and compositional factors have all contributed to the optimum low resistivity occurring at this plasma power. The grain size exhibits a maximum in the 1.25 - 1.5 kW range and there is improved (002) orientation, minimising grain boundary scattering. The highest carrier concentration and mobility was observed at the plasma power of 1.5 kW which may be associated with the maximum in the aluminium doping concentration (3.0 at.%). The lowest residual stress is also observed at 1.5 kW.

MARK ALAN BAKER, Xinnan Lu, Dalaver H. Anjum, Georgia Basina, STEVEN JOHN HINDER, Wassilios Papawassiliou, Andrew J. Pell, Marina Karagianni, Georgios Papavassiliou, Dinesh Shetty, Dina Abdullah Ali Gaber, Safa Abdullah Ali Gaber, Yasser Al Wahedi, Kyriaki Polychronopoulou (2021)Ni2P Nanoparticles Embedded in Mesoporous SiO2 for Catalytic Hydrogenation of SO2 to Elemental S, In: ACS Applied Nano Material American Chemical Society

Highly active nickel phosphide nano clusters (Ni2P) confined in mesoporous SiO2 catalyst were synthesized by a two-step process targeting tight control over the Ni2P size and phase. The Ni precursor was incorporated into the MCM-41 matrix by one-pot synthesis, followed by the phosphorization step which was accomplished in oleylamine with trioctylphosphine at 300 oC so to achieve the phase transformation from Ni to Ni2P. For benchmarking, Ni confined by the mesoporous SiO2 (absence of phosphorization) and 11 nm Ni2P nanoparticles (absence of SiO2), were also prepared. From the microstructural analysis, it was found that the growth of Ni2P nano clusters was restricted by the mesoporous channels, thus forming ultrafine and highly dispersed Ni2P nano clusters (< 2 nm). The above approach led to promising catalytic performance following the order: u-Ni2P@m-SiO2 > n-Ni2P > u-Ni@m-SiO2 > c-Ni2P in the selective hydrogenation of SO2 to S. In particular, u-Ni2P@m-SiO2 exhibited an SO2 conversion of 94 % at 220 oC and ~99 % at 240 oC, which is higher than the 11 nm stand-alone Ni2P particles (43 % at 220 oC and 94 % at 320 oC), highlighting the importance of the role played by SiO2 in stabilizing ultrafine nanoparticles of Ni2P. The reaction activation energy Ea over u-Ni2P@m-SiO2 is ~33 kJ/mol, which is lower than over n-Ni2P (~36 kJ/mol) and c-Ni2P (~66 kJ/mol), suggesting that the reaction becomes energetically favored over the ultrafine Ni2P nano clusters.

Xinnan Lu, MARK ALAN BAKER, Dalaver H. Anjum, Wassilios Papawassiliou, Andrew J. Pell, Michael Fardis, Georgios Papavassiliou, STEVEN JOHN HINDER, Safa Abdullah Ali Gaber, Dina Abdullah Ali Gaber, Yasser Al Wahedi, Kyriaki Polychronopoulou (2021)Nickel Phosphide Nanoparticles for Selective Hydrogenation of SO2 to H2S, In: ACS Applied Nano Material American Chemical Society

Highly mesoporous SiO2 encapsulated NixPy crystals, where (x, y) = (5, 4), (2, 1), and (12, 5) were successfully synthesized by adopting thermolytic method using oleylamine (OAm), trioctylphosphine (TOP) and trioctylphosphine oxide (TOPO). The Ni5P4@SiO2 system shows the highest reported activity for the selective hydrogenation of SO2 towards H2S at 320 oC (96 % conversion of SO2 and 99 % selectivity to H2S) which was superior to the activity of the commercial CoMoS@Al2O3 catalyst (64 % conversion of SO2 and 71 % selectivity to H2S at 320 oC). The morphology of the Ni5P4 crystal was finely tuned via adjustment of the synthesis parameters receiving a wide spectrum of morphologies (hollowed, macroporous-network and SiO2 confined ultra-fine clusters). Intrinsic characteristics of the materials were studied using XRD, HRTEM/STEM-HAADF, EDX, BET, H2-TPR, XPS, and experimental and calculated 31P MAS ssNMR towards establishing the structure-performance correlation for the reaction of interest. Characterization of the catalysts after the SO2 hydrogenation reaction proved the preservation of the morphology, crystallinity and Ni/P ratio for all the catalysts.

James R. Clark, Ying Chen, Steven Hinder, S. Ravi P. Silva (2017)Highly Sensitive Dopamine Detection Using a Bespoke Functionalised Carbon Nanotube Microelectrode Array, In: Electroanalysis29(10)pp. 2365-2376 Wiley

Understanding how the brain works requires developing advanced tools that allow measurement of bioelectrical and biochemical signals, including how they propagate between neurons. The introduction of nanomaterials as electrode materials has improved the impedance and sensitivity of microelectrode arrays (MEAs), allowing high quality recordings of single cells insitu using electrode diameters of

Kyriaki Polychronopoulou, Ayesha A AlKhoori, Angelos M Efstathiou, Maguy Abi Jaoude, C. M Damaskinos, Mark A Baker, Alia Almutawa, Dalaver H Anjum, Michalis A Vasiliades, Abderrezak Belabbes, Lourdes F Vega, Abdallah Fathy Zedan, Steven J Hinder (2021)Design Aspects of Doped CeO2 for Low-Temperature Catalytic CO Oxidation: Transient Kinetics and DFT Approach, In: ACS applied materials & interfaces13(19)pp. 22391-22415 American Chemical Society

CO elimination through oxidation over highly active and cost-effective catalysts is a way forward for many processes of industrial and environmental importance. In this study, doped CeO2 with transition metals (TM = Cu, Co, Mn, Fe, Ni, Zr, and Zn) at a level of 20 at. % was tested for CO oxidation. The oxides were prepared using microwave-assisted sol–gel synthesis to improve catalyst’s performance for the reaction of interest. The effect of heteroatoms on the physicochemical properties (structure, morphology, porosity, and reducibility) of the binary oxides M–Ce–O was meticulously investigated and correlated to their CO oxidation activity. It was found that the catalytic activity (per gram basis or TOF, s–1) follows the order Cu–Ce–O > Ce–Co–O > Ni–Ce–O > Mn–Ce–O > Fe–Ce–O > Ce–Zn–O > CeO2. Participation of mobile lattice oxygen species in the CO/O2 reaction does occur, the extent of which is heteroatom-dependent. For that, state-of-the-art transient isotopic 18O-labeled experiments involving 16O/18O exchange followed by step-gas CO/Ar or CO/O2/Ar switches were used to quantify the contribution of lattice oxygen to the reaction. SSITKA-DRIFTS studies probed the formation of carbonates while validating the Mars–van Krevelen (MvK) mechanism. Scanning transmission electron microscopy-high-angle annular dark field imaging coupled with energy-dispersive spectroscopy proved that the elemental composition of dopants in the individual nanoparticle of ceria is less than their composition at a larger scale, allowing the assessment of the doping efficacy. Despite the similar structural features of the catalysts, a clear difference in the Olattice mobility was also found as well as its participation (as expressed with the α descriptor) in the reaction, following the order αCu > αCo> αMn > αZn. Kinetic studies showed that it is rather the pre-exponential (entropic) factor and not the lowering of activation energy that justifies the order of activity of the solids. DFT calculations showed that the adsorption of CO on the Cu-doped CeO2 surface is more favorable (−16.63 eV), followed by Co, Mn, Zn (−14.46, −4.90, and −4.24 eV, respectively), and pure CeO2 (−0.63 eV). Also, copper compensates almost three times more charge (0.37e −) compared to Co and Mn, ca. 0.13e − and 0.10e −, respectively, corroborating for its tendency to be reduced. Surface analysis (X-ray photoelectron spectroscopy), apart from the oxidation state of the elements, revealed a heteroatom–ceria surface interaction (Oa species) of different extents and of different populations of Oa species.

Deborah Charlton, Catia Costa, Gustavo F. Trindade, Steve Hinder, John F. Watts, Melanie J. BAILEY (2023)Improving the technological readiness of Time of Flight-Secondary Ion Mass Spectrometry for enhancing fingermark recovery - towards operational deployment  , In: Science & justice : journal of the Forensic Science Society63(1)pp. 9-18 Elsevier

The processes routinely used by police forces to visualise fingermarks in casework may not provide sufficient ridge pattern quality to aid an investigation. Time of Flight-Secondary Ion Mass Spectrometry (ToF-SIMS) has been proposed as a technique to enhance fingermark recovery. The technique is currently designated a Category C process in the Fingermark Visualisation Manual (FVM) as it shows potential for effective fingermark visualisation but has not yet been fully evaluated. Here the sensitivity of ToF-SIMS on three common exhibit-type surfaces - paper, polyethylene and stainless-steel was compared to standard processes. An adapted Home Office grading scale was used to evaluate the efficacy of fingerprint development by ToF-SIMS and to provide a framework for comparison with standard processes. ToF-SIMS was shown to visualise more fingerprints than the respective standard process, for all surfaces tested. In addition, ToF-SIMS was applied after the standard processes and successfully enhanced the fingerprint detail, even when the standard process failed to visualise ridge detail. This demonstrates the benefit for incorporating it into current operational fingermark development workflows. Multivariate analysis (MVA), using simsMVA, was additionally explored as a method to simplify the data analysis and image generation process.

Pavlos Giannakou, Mateus G. Masteghin, Robert C. T. Slade, Steven J. Hinder, Maxim Shkunov (2019)Energy storage on demand: ultra-high-rate and high-energy-density inkjet-printed NiO micro-supercapacitors, In: Journal of Materials Chemistry A: materials for energy and sustainability7(37)pp. 21496-21506 Royal Society of Chemistry

Micro-supercapacitors are an important class of energy storage devices for portable, self-powered and miniaturized electronics such as sensors, biomedical implants and RFID tags. To address the issue of limited energy density of micro-supercapacitors, pseudocapacitive transition-metal oxides have been used as electrodes at the cost of lower power capability due to their low electronic conductivity. In this work, high-energy-density and high-power-density nickel(ii) oxide (NiO) micro-supercapacitors, fabricated through inkjet printing, are demonstrated. The nanoparticle-based thin film NiO electrodes showed up to 14 orders of magnitude higher electrical conductivity than single crystal NiO. The enhanced conductivity of the electrodes was reflected in the low relaxation time constant of just 30 ms, which is among the lowest achieved for any supercapacitor. A magnesium perchlorate-based aqueous electrolyte with extended operating voltage window was developed to enable the operation of the devices up to 1.5 V. The devices showed remarkable areal and volumetric specific capacitances of up to 155 mF cm(-2) and 705 F cm(-3) respectively, surpassing the state-of-the-art inkjet-printed supercapacitors but also a few of the best micro-supercapacitors known to date. This work provides a compelling platform to simplify the fabrication process of micro-supercapacitors, with focus on digital design, scalable manufacturing, and direct integration with printed electronics.

G.I. Siakavelas, N.D. Charisiou, AA AlKhoori, V. Sebastian, S.J. Hinder, MARK ALAN BAKER, I.V. Yentekakis, K. Polychronopoulou, M.A. Goula (2022)Cerium oxide catalysts for oxidative coupling of methane reaction: Effect of lithium, samarium and lanthanum dopants, In: Journal of Environmental Chemical Engineering10(2)107259 Elsevier

The work presented herein reports on the oxidative coupling of methane (OCM) performance of a series of Li-free and Li-doped CeO2 and CeO2 modified with Sm3+ and La3+ catalysts. The supporting materials (Ce, Sm-Ce and La-Sm-Ce metal oxides) were synthesized using the microwave assisted sol-gel method in order to achieve nanophase complex materials with increased particle surface energy and reactivity. Lithium ions were added, using the wet impregnation technique, in order to further improve the physicochemical characteristics and reinforce the activity and selectivity, in terms of C2H6 and C2H4 production. All materials were characterized using N2 adsorption-desorption, XRD, Raman spectroscopy, CO2-TPD, H2-TPR, SEM and XPS. We showed that the addition of lithium species changed the reaction pathway and drastically enhanced the production of ethylene and ethane, mainly for the promoted catalysts (Li/Sm-Ce and Li/La-Sm-Ce). In particular, the presence and the synergy between the electrophilic oxygen species (peroxide and superoxide), population of oxygen vacancy sites and the surface moderate basic sites determined the reaction pathway and the desirable product distribution.

J. L. Hall, C. J. Bevas, S. J. Hinder, E.L. Kynaston, I. Lindsay, P. Gruber, J. L. Keddie (2022)Environmental Effects on the Coefficient of Friction and Tack Adhesion of Formulated Waterborne Coatings, In: Frontiers of Mechanical Engineering7796853 Springer

Waterborne coatings emit a low amount of harmful volatile organic compounds (VOCs) into the atmosphere compared to solvent-cast coatings. A typical waterborne formulation for agricultural applications consists of colloidal thermoplastic particles (latex) as the binder, a thickener to raise the viscosity, inorganic filler particles with a water-soluble dispersant, and a colloidal wax to modify surface properties. The formulations typically contain hygroscopic species that are potentially subject to softening by environmental moisture. The hardness, tack adhesion, and coefficient of friction of formulated coatings determines their suitability in applications. However, the relationship of these properties to the components in a coating formulation has not been adequately explored. Furthermore, the relationship between hygroscopic components and properties is an added complication. Here, we have characterized the hardness and tack adhesion of model formulated coatings using a single micro-indentation cycle with a conical indenter under controlled temperatures (above and below the glass transition temperature of a latex binder) and relative humidities. In parallel, we measured the coefficient of kinetic friction, μk, for the same coatings using a bespoke testing rig under controlled environmental conditions. Across a range of temperatures, RH and compositions, we find an inverse correlation between the coating hardness and μk. Any correlation of μk with the roughness of the coatings, which varies with the composition, is less clear. Formulations that contain wax additives have a higher μk at a low RH of 10%, in comparison to formulations without wax. For the wax formulations, μk decreases when the RH is raised, whereas in non-wax formulations, μk increases with increasing RH. Wax-containing coatings are hydrophilic (with a lower water contact angle), however the wax has a lower water permeability. A lubricating layer of water can explain the lower observed μk in these formulations. The addition of wax is also found to planarize the coating surface, which leads to higher tack adhesion in dry coatings in comparison to coatings without wax. Greater adhesive contact in these coatings can explain their higher friction. Our systematic research will aid the design of seed coating formulations to achieve their optimum properties under a wide range of environmental conditions.

SJ Hinder, JF Watts (2010)SIMS fingerprint analysis on organic substrates, In: Surface and Interface Analysis42(6-7)pp. 826-829
JM Ferreira, JL Rossi, MA Baker, SJ Hinder, I Costa (2014)Deposition and Characterization of a New Mixed Organic/Inorganic Cerium Containing Coating for the Corrosion Protection of Eletrogalvanized Steel, In: INTERNATIONAL JOURNAL OF ELECTROCHEMICAL SCIENCE9(4)pp. 1827-1839 ESG

Protective coatings have been deposited on electrogalvanized steel by immersion in solutions containing 2-Butyne-1.4-diol propoxylate (CHO), cerium nitrate, sodium nitrate and sodium sulphate for different immersion periods. The surface morphology and chemical composition of the coatings formed on the electrogalvanized steel were studied using field emission gun scanning electron microscopy, X-ray photoelectron spectroscopy and Fourier Transform Infrared Spectroscopy. The corrosion resistance of the electrogalvanized steel prior to and after surface treatment was investigated by electrochemical impedance spectroscopy in 0.1 mol L NaCl solution. The results were compared to the performance of a chromate conversion coating in the same solution. The coatings formed on the electrogalvanized steel surface showed the presence of a mixed organic/inorganic layer containing CeO and CeO which improved the corrosion resistance of the substrate and showed a superior corrosion resistance to that provided by a chromate conversion coating.

MJ Bailey, BN Jones, RP Webb, S Hinder, J Watts, S Bleay (2010)Depth Profiling of Fingerprints and ink signals by SIMS and MeV SIMS, In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms268(11-12)pp. 1929-1932
PG Jenkins, L Yang, JL Thomason, JJ Liggat, SJ Hinder, JF Watts (2014)Regeneration of thermally recycled glass fibre for cost-effective composite recycling: Fundamental study of strength loss of thermally conditioned glass fibre, In: 16th European Conference on Composite Materials, ECCM 2014

Data produced using both unsized and aminopropyltriethoxysilane (APS) coated fibre will be shown and discussed. By applying a novel method of single fibre thermal conditioning (sf-TC) it was found that retained fibre strength is, in some cases, underestimated and that the temperature range 400-500 °C is the most critical for thermally induced strength loss. This is not related to degradation of the APS surface coating, but rather is likely linked to fundamental changes occurring in the glass network or at the fibre surface. X-ray Photoelectron Spectroscopy (XPS) analysis of treated fibres was performed, but it was not possible to measure any significant changes in surface chemical state. Analysis of water volatilized from unsized fibre was performed using a furnace connected to quadropole mass spectrometer. An asymptotic minimum in volatilized water is reached between 400-500 °C.

SJ Hinder, JF Watts, C Lowe (2006)Surface and interface analysis of complex polymeric paint formulations, In: SURFACE AND INTERFACE ANALYSIS38(4)pp. 557-560
Nikolaos Charisiou, Georgios Siakavelas, Victor Sebastian , STEVEN JOHN HINDER, MARK ALAN BAKER, Vagelis Papadakis, Wen Wang , Kyriaki Polychronopoulou, Maria Goula (2020)Structural Investigation of the Carbon Deposits on Ni/Al2O3 Catalyst Modified by CaO-MgO for the Biogas Dry Reforming Reaction

Ni/Al2O3 and Ni/CaO-MgO-Al2O3 catalysts were investigated for the biogas dry reforming reaction using CH4/CO2 mixtures with minimal dilution. Stability tests were conducted between 600 and 800 oC and TGA/DTG, Raman, STEM-HAADF, HR-TEM, XPS techniques were used to characterize the spent samples. Graphitized carbon allotrope structures, carbon nanotubes (CNTs) and amorphous carbon were formed on all samples. Metallic Ni0 was recorded for all (XPS), whereas a strong peak corresponding to Ni2O3/NiAl2O4 was observed for the Ni/Al2O3 sample (650–750°C). Stability tests confirmed that the Ni/CaO-MgO-Al2O3 catalyst deactivates at a more gradual rate and is more active and selective in comparison to the Ni/Al2O3 for all temperatures. The Ni/CaO-MgO-Al2O3 exhibits good durability in terms of conversion and selectivity, whereas the Ni/Al2O3 gradually loses its activity in CH4 and CO2 conversion, with a concomitant decrease of the H2 and CO yield. It can be concluded that doping Al2O3 with CaO-MgO enhances catalytic performance by: (a) maintaining the Ni0 phase during the reaction, due to higher dispersion and stronger active phase-support interactions, (b) leading to a less graphitic and more defective type of deposited carbon, and (c) facilitating the deposited carbon gasification due to the enhanced CO2 adsorption on its increased surface basic sites.