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46 items found (0 items not approved), displaying 1 to 10.[First/Prev] 1, 2, 3, 4, 5 [Next/Last]

Instruments / Technical Area	Publication Details	Published
	A single-source precursor approach to solution processed indium arsenide thin films Peter Marchand , Sanjayan Sathasivam , Benjamin A. D. Williamson , David Pugh , Salem M. Bawaked , Sulaiman N. Basahel , Abdullah Y. Obaid , David O. Scanlon , Ivan P. Parkin , Claire J. Carmalt Journal Of Materials Chemistry C 4, 6761 - 6768 DOI: 10.1039/C6TC02293F Open Access Show Abstract ▼ Abstract: This paper reports the synthesis of the novel single-source precursor, [{(MeInAstBu)3}2(Me2InAs(tBu)H)2] and the subsequent first report of aerosol-assisted chemical vapour deposition of InAs thin films. Owing to the use of the single-source precursor, highly crystalline and stoichiometric films were grown at a relatively low deposition temperature of 450 °C. Core level XPS depth profiling studies showed some partial oxidation of the film surface, however this was self-limiting and disappeared on etch profiles. Valence band XPS analysis matched well with the simulated density of state spectrum. Hall effect measurements performed on the films showed that the films were n-type with promising resistivity (3.6 × 10−3 Ω cm) and carrier mobility (410 cm2 V−1 s−1) values despite growth on amorphous glass substrates.	Jun 2016
I18-Microfocus Spectroscopy	Aerosol assisted chemical vapor deposition of transparent conductive zinc oxide films Davinder S. Bhachu , Gopinathan Sankar , Ivan P. Parkin Chemistry Of Materials 24 (24), 4704 - 4710 DOI: 10.1021/cm302913b Diamond Proposal Number(s): [8374] Show Abstract ▼ Abstract: Highly conductive and transparent ZnO films were synthesized by the reaction of diethyl zinc (in toluene) with methanol by dual source aerosol assisted chemical vapor deposition. These films displayed a stable sheet resistance of 7.2 Ω/□ and high transmission across the visible region comparable to commercial transparent conducting oxides (TCOs) based on oxides of tin or indium. Doping the zinc oxide structure with fluorine (trifluorotoluene) resulted in dense compact films with improved electrical properties than ZnO films with a sheet resistance of 4.5 Ω/□. These films also displayed idealized surface texturing for photovoltaic applications. Fluorine concentration was 2 at.% determined by wavelength dispersive X-ray analysis (WDX). Aluminum doped zinc oxide films were also synthesized by introducing dopant amounts of trimethylaluminium solution (in toluene) into the system. These films exhibited low sheet resistances of 14 Ω/□. The aluminum concentration in the films was 4 at.% determined by WDX.	Dec 2012
B18-Core EXAFS	An EXAFS study on the photo-assisted growth of silver nanoparticles on titanium dioxide thin-films and the identification of their photochromic states Ivan P. Parkin , Claire J. Carmault , Stephen A. Parry , Andreas Kafizas , Alan V. Chadwick Physical Chemistry Chemical Physics DOI: 10.1039/c3cp44513e Diamond Proposal Number(s): [7134] Show Abstract ▼ Abstract: Anatase TiO2 thin-films were formed on glass by a sol–gel dip-coating method and annealed at 500 °C. Ag nanoparticles were grown on the surface of TiO2 by a photo-assisted process from AgNO3 salt using either UVC – 254 nm or UVA – 365 nm light. The size, shape and coverage of the particles were assessed by scanning electron microscopy. Changes in surface plasmon properties were investigated by UV-visible spectroscopy. A greater level of spherical Ag nanoparticles grew on TiO2 when using UVA light (365 nm); with particles 96 ± 33 nm wide on average and covering 29% of the surface. In the case of UVC light (254 nm), particles were 78 ± 14 nm wide on average and covered 13% of the surface. EXAFS measurements performed in situ of the Ag K-edge showed that the photo-assisted growth was more rapid when UVA light was used, leading to the full conversion of the AgNO3 salt layer in ≈1900 seconds. When UVC light was used, ≈50% of the salt layer was converted in ≈6100 seconds. The inhibited growth under UVC conditions was attributed to the absorption of light by the Ag nanoparticles as they formed (as opposed to the semiconductor beneath). The films also displayed reversible photochromism. The change in phase from the coloured (metallic Ag) to the bleached state (oxidized Ag) was identified using EXAFS spectroscopy. By comparing the EXAFS pattern with simulated model structures, it was shown that the transition from cubic Ag to cubic Ag2O was most likely, with an ≈70% conversion with 12 hours of white light irradiance. We believe that this is the first time the bleached form of silver in photochromic Ag–TiO2 thin-films has been identified by a direct method. In addition, we believe that this is the first case in which the photo-assisted formation of Ag–TiO2 has been monitored in situ under ambient temperature and pressure.	Apr 2013
E01-JEM ARM 200CF E02-JEM ARM 300CF I20-Scanning-X-ray spectroscopy (XAS/XES)	Approaching theoretical performances of electrocatalytic hydrogen peroxide generation by cobalt‐nitrogen moieties Runjia Lin , Liqun Kang , Karolina Lisowska , Weiying He , Siyu Zhao , Shusaku Hayama , Dan Brett , Graham Hutchings , Furio Corà , Ivan Parkin , Guanjie He Angewandte Chemie International Edition DOI: 10.1002/anie.202301433 Diamond Proposal Number(s): [29254, 29207] Open Access Show Abstract ▼ Abstract: Electrocatalytic oxygen reduction reaction (ORR) has been intensively studied for efficient and environmentally benign energy conversion processes. However, insufficient understanding of ORR 2e--pathway mechanism at the atomic level inhibits rational design of electrocatalysts with both high activity and selectivity, causing concerns including catalyst degradation due to Fenton reaction or poor efficiency of H2O2 electrosynthesis. Herein we show that the generally accepted ORR electrocatalyst design based on a Sabatier volcano plot argument optimises activity but is unable to account for the 2e--pathway selectivity; an extended “dynamic active site saturation” model that examines in addition the hydrogenation kinetics linked to the OOH* adsorption energy enables us to resolve the activity-selectivity compromise. Through electrochemical and operando spectroscopic studies on the ORR process governed by a series of Co-N x /carbon nanotube hybrids, a construction-driven approach that aims to create the maximum number of 2e- ORR sites by directing the secondary ORR electron transfer step towards the 2e- intermediate is proven to be attainable by manipulating O2 hydrogenation kinetics. Control experiments reveal the O2 hydrogenation chemistry is related to a catalyst reconstruction with lower symmetry around the Co active centre induced by the application of a cathodic potential. The optimised catalyst exhibits a ~100% H2O2 selectivity and an outstanding activity with an ORR potential of 0.82 V versus the reversible hydrogen electrode to reach the ring current density of 1 mA cm-2 by using rotating ring-disk electrode measurement, which is the best-performing 2e- ORR electrocatalyst reported to date, and approaches the thermodynamic limit.	Mar 2023
	Bismuth oxyhalides: synthesis, structure and photoelectrochemical activity Davinder S. Bhachu , Savio J. A. Moniz , Sanjayan Sathasivam , David O. Scanlon , Aron Walsh , Salem M. Bawaked , Mohamed Mokhtar , Abdullah Y. Obaid , Ivan P. Parkin , Junwang Tang , Claire J. Carmalt Chemical Science 7, 4832-4841 DOI: 10.1039/C6SC00389C Open Access Show Abstract ▼ Abstract: We report the synthesis and photoelectrochemical assessment of phase pure tetragonal matlockite structured BiOX (where X = Cl, Br, I) films. The materials were deposited using aerosol-assisted chemical vapour deposition. The measured optical bandgaps of the oxyhalides, supported by density functional theory calculations, showed a red shift with the increasing size of halide following the binding energy of the anion p-orbitals that form the valence band. Stability and photoelectrochemical studies carried out without a sacrificial electron donor showed the n-type BiOBr film to have the highest photocurrent reported for BiOBr in the literature to date (0.3 mA cm−2 at 1.23 V vs. RHE), indicating it is an excellent candidate for solar fuel production with a very low onset potential of 0.2 V vs. RHE. The high performance was attributed to the preferred growth of the film in the [011] direction, as shown by X-ray diffraction, leading to internal electric fields that minimize charge carrier recombination.	Mar 2016
E02-JEM ARM 300CF	Cathode–electrolyte interface modification by binder engineering for high-performance aqueous zinc-ion batteries Haobo Dong , Ruirui Liu , Xueying Hu , Fangjia Zhao , Liqun Kang , Longxiang Liu , Jianwei Li , Yeshu Tan , Yongquan Zhou , Dan J. L. Brett , Guanjie He , Ivan Parkin Advanced Science 334 DOI: 10.1002/advs.202205084 Diamond Proposal Number(s): [30614, 29809] Open Access Show Abstract ▼ Abstract: A stable cathode–electrolyte interface (CEI) is crucial for aqueous zinc-ion batteries (AZIBs), but it is less investigated. Commercial binder poly(vinylidene fluoride) (PVDF) is widely used without scrutinizing its suitability and cathode-electrolyte interface (CEI) in AZIBs. A water-soluble binder is developed that facilitated the in situ formation of a CEI protecting layer tuning the interfacial morphology. By combining a polysaccharide sodium alginate (SA) with a hydrophobic polytetrafluoroethylene (PTFE), the surface morphology, and charge storage kinetics can be confined from diffusion-dominated to capacitance-controlled processes. The underpinning mechanism investigates experimentally in both kinetic and thermodynamic perspectives demonstrate that the COO− from SA acts as an anionic polyelectrolyte facilitating the adsorption of Zn2+; meanwhile fluoride atoms on PTFE backbone provide hydrophobicity to break desolvation penalty. The hybrid binder is beneficial in providing a higher areal flux of Zn2+ at the CEI, where the Zn-Birnessite MnO2 battery with the hybrid binder exhibits an average specific capacity 45.6% higher than that with conventional PVDF binders; moreover, a reduced interface activation energy attained fosters a superior rate capability and a capacity retention of 99.1% in 1000 cycles. The hybrid binder also reduces the cost compared to the PVDF/NMP, which is a universal strategy to modify interface morphology.	Dec 2022
	Chemical vapor deposition of photocatalytically active pure Brookite TiO2 thin films Abdullah M. Alotaibi , Sanjayan Sathasivam , Benjamin A. D. Williamson , Andreas Kafizas , Carlos Sotelo-Vazquez , Alaric Taylor , David O. Scanlon , Ivan P. Parkin Chemistry Of Materials DOI: 10.1021/acs.chemmater.7b04944 Show Abstract ▼ Abstract: Brookite is the least investigated phase of TiO2 due to the synthetic difficulty of obtaining the pure phase. Here, we present the first ever chemical vapor deposition synthesis of pure brookite TiO2 thin films. The films were highly crystalline and phase pure as determined by X-ray diffraction and Raman spectroscopy studies. Scanning electron microscopy studies showed the films to have a structured morphology consisting of pyramidal features. The photocatalytic properties of the brookite film, tested using stearic acid under UVA (365 nm) irradiation, were superior to both an anatase film grown under similar conditions and NSG Activ glass. Transient absorption spectroscopy showed that the innate electron–hole recombination dynamics are similar in brookite and anatase, akin to previous reports. The superior activity of the brookite film is hence attributed to the higher surface area compared to anatase.	Feb 2018
	Chemical vapor deposition synthesis and optical properties of Nb2O5 thin films with hybrid functional theoretical insight into the band structure and band gaps Sanjayan Sathasivam , Benjamin A. D. Williamson , Shaeel A. Al Thabaiti , Abdullah Y. Obaid , Sulaiman N. Basahel , Mohamed Mokhtar , David O. Scanlon , Claire J. Carmalt , Ivan P. Parkin Acs Applied Materials & Interfaces DOI: 10.1021/acsami.7b00907 Show Abstract ▼ Abstract: Nb2O5 is an important material able to exist in many polymorphs with unique optical properties and morphologies that are dependent on the synthetic route. Here we report a novel ambient pressure chemical vapour deposition route to Nb2O5 via aerosol assisted chemical vapour deposition. The amorphous as deposited films were annealed in air to obtain the three most stable crystal structures - orthorhombic, tetragonal and monoclinic. The films were thoroughly characterized for their material properties and an in depth study into the optical properties was carried out using state of the art hybrid functional theory that allowed more insight into the optical properties of the materials	May 2017
	Combinatorial atmospheric pressure chemical vapor deposition of F:TiO2; the relationship between photocatalysis and transparent conducting oxide properties Andreas Kafizas , Nuruzzaman Noor , Penelope Carmichael , David O. Scanlon , Claire J. Carmalt , Ivan P. Parkin Advanced Functional Materials 24 (12), 1758 - 1771 DOI: 10.1002/adfm.201301333 Show Abstract ▼ Abstract: Combinatorial atmospheric pressure chemical vapor deposition (APCVD) is used to deposit anatase TiO2 with a graded level of F-doping between 1.10 ≤ F:Ti (at%) ≤ 2.57 from the reaction of titanium tetrachloride, ethyl acetate and trifluoroacetic acid at 500 °C on glass. The photocatalytic activity and electrical resistivity of 200 allotted positions across a grid are screened using high-throughput techniques. A blue region of film is singled out for containing the lowest electrical resistivities of any previously reported doped or undoped TiO2-based system formed by APCVD (ρ ≈ 0.22–0.45 Ω cm, n = 0.8–1.2 × 1018 cm−3, μ = 18–33 cm2 V−1 s−1). The blue region contains a lower fluorine doping level (F:Ti ≈ 1.1–1.6%, Ebg ≈ 3.06 eV) than its neighboring colorless region (F:Ti ≈ 2.3–2.6%, Ebg ≈ 3.15–3.21 eV, ρ ≈ 0.61–1.3 Ω cm). State-of-the-art hybrid density functional theory calculations were employed to elucidate the nature of the different doping behaviors. Two distinct fluorine doping environments were present. At low concentrations, F substituting for O (FO) dominates, forming blue F:TiO2. At high concentrations, negatively charged fluorine interstitials (Fi−1) begin to dominate, forming transparent F:TiO2.	Mar 2014
	Computational and experimental study of Ta2O5 thin films Sanjayan Sathasivam , Benjamin A. D. Williamson , Andreas Kafizas , Shaeel A. Althabaiti , Abdullah Y. Obaid , Sulaiman N. Basahel , David O. Scanlon , Claire J. Carmalt , Ivan P. Parkin The Journal Of Physical Chemistry C DOI: 10.1021/acs.jpcc.6b11073 Show Abstract ▼ Abstract: This paper reports the novel synthesis of amorphous Ta2O5 and the subsequent isolation of the orthorhombic (β) crystallographic phase, using aerosol-assisted chemical vapor deposition. Hybrid density functional theory was used to obtain the calculated optical band gap (3.83 eV) for the first time, which closely matches our experimental findings (3.85 eV). The films were highly transparent in the visible and near-IR region of the electromagnetic spectrum. The refractive indexes, calculated using the Swanepoel method, showed good agreement with literature findings. The photocatalytic properties of the films, determined through the photominerilization of stearic acid under 254 nm radiation showed the amorphous sample to be an order of magnitude superior over crystalline β-Ta2O5.	Jan 2017

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