A5036502498- Advanced Photocatalysis Techniques
- Electrocatalysts for Energy Conversion
- Copper-based nanomaterials and applications
- Gas Sensing Nanomaterials and Sensors
- Water Quality Monitoring and Analysis
- Catalytic Processes in Materials Science
- TiO2 Photocatalysis and Solar Cells
- Electronic and Structural Properties of Oxides
- Electrochemical Analysis and Applications
- ZnO doping and properties
- Perovskite Materials and Applications
- Advanced Semiconductor Detectors and Materials
- Solar-Powered Water Purification Methods
- Ga2O3 and related materials
- Fuel Cells and Related Materials
- Conducting polymers and applications
- Nanowire Synthesis and Applications
- Transition Metal Oxide Nanomaterials
- Quantum Dots Synthesis And Properties
- CO2 Reduction Techniques and Catalysts
- Thermochemical Biomass Conversion Processes
- Metalloenzymes and iron-sulfur proteins
- Coal Properties and Utilization
- MXene and MAX Phase Materials
- Metallurgical and Alloy Processes
Imperial College London
2015-2024
Centre for Process Innovation
2021
Transnational Press London
2018-2019
New Mexico State University
1984
Oxygen vacancies are ubiquitous in metal oxides and critical to performance, yet the impact of these states upon charge carrier dynamics important for photoelectrochemical photocatalytic applications remains contentious poorly understood. A key challenge is unambiguous identification spectroscopic fingerprints which can be used track their function. Herein, we employ five complementary techniques modulate electronic occupancy associated with oxygen situ BiVO4 photoanodes, allowing us...
Abstract Ni/Fe oxyhydroxides are the best performing Earth-abundant electrocatalysts for water oxidation. However, origin of their remarkable performance is not well understood. Herein, we employ spectroelectrochemical techniques to analyse kinetics oxidation on a series oxyhydroxide films: FeOOH, FeOOHNiOOH, and Ni(Fe)OOH (5% Fe). The concentrations reaction rates oxidised states accumulated during catalysis determined. found exhibit fastest but accumulates fewer states, resulting in...
A thorough understanding of the kinetic competition between desired water oxidation/electron extraction processes and any detrimental surface recombination is required to achieve high oxidation efficiencies in transition-metal oxide systems. The kinetics these Faradaic efficiency tungsten trioxide (WO3) photoanodes (>85%) are monitored herein by transient diffuse reflectance spectroscopy correlated with photocurrent data for electron extraction. Under anodic bias, efficient hole transfer...
Unveiling the role of applied bias on charge carrier dynamics in WO<sub>3</sub>/BiVO<sub>4</sub> junction during water oxidation.
This study reports a comparison of the kinetics electrochemical (EC) versus photoelectrochemical (PEC) water oxidation on bismuth vanadate (BiVO4) photoanodes. Plots current density surface hole density, determined from operando optical absorption analyses under EC and PEC conditions, are found to be indistinguishable. We thus conclude that is driven by Zener effect tunneling electrons valence conduction band strong bias, with both being accumulated holes. further demonstrate our combined...
Catalyst modification of metal oxide photoanodes can result in markedly improved water oxidation efficiency. However, the reasons for improvement are often subtle and controversial. Upon depositing a CoFe Prussian blue (CoFe-PB) catalyst on BiVO4, large photocurrent increase onset potential shift (up to 0.8 V) observed, resulting substantially more efficient system with high stability. To elucidate origin this enhancement, we used time-resolved spectroscopies compare dynamics photogenerated...
In metal oxide-based photoelectrochemical devices, the spatial separation of photogenerated electrons and holes is typically attributed to band-bending at oxide/electrolyte interface. However, direct evidence such impacting upon charge carrier lifetimes has been very limited date. Herein we use ultrafast spectroscopy track rapid relaxation in space-charge layer their recombination with trapped WO3 photoanodes. We observe that applied bias can significantly increase on all time scales from...
Elucidating the role of charge accumulation and reaction kinetics in governing performance Ni/Fe oxyhydroxides as electrocatalysts co-catalysts on BiVO<sub>4</sub> photoanodes water oxidation.
A limiting factor to the efficiency of water Oxygen Evolution Reaction (OER) in metal oxide nanoparticle photocatalysts is rapid recombination holes and electrons. Facet-engineering can effectively improve charge separation and, consequently, OER efficiency. However, kinetics behind this improvement remain poorly understood. This study utilizes photoinduced absorption spectroscopy investigate yield facet-engineered BiVO
The electron-donating ability of the sacrificial agent and protonation catalyst determine optimum pH for hydrogen production.
Abstract Ionic carbon nitrides based on poly(heptazine imides) (PHI) represent a vigorously studied class of materials with possible applications in photocatalysis and energy storage. Herein, for the first time, photogenerated charge dynamics highly stable binder‐free PHI photoanodes using operando transient photocurrents spectroelectrochemical photoinduced absorption measurements is studied. It discovered that light‐induced accumulation long‐lived trapped electrons within film leads to...
In photoelectrochemical cells (PECs) the photon-to-current conversion efficiency is often governed by carrier transport. Most metal oxides used in PECs exhibit thermally activated transport due to charge localization via formation of polarons or interaction with defects. This impacts catalysis restricting accumulation and extraction. To overcome this bottleneck nanostructuring, selective doping photothermal treatments have been employed. Here we demonstrate an alternative approach capable...
A new approach for the study of photocatalytic heterojunctions based on a layer-by-layer PDOS has been developed. Our combination experimental and theoretical calculations reveals importance interfacial effects when heterojunction is formed that can dictate performance heterojunction.
Bi2WO6 is one of the simplest members versatile Aurivillius oxide family materials. As an intriguing model system for oxides, BiVO4 exhibits low water oxidation onset potentials (∼0.5–0.6 VRHE) driven solar oxidation. Despite this, also produces photocurrents in comparison to other metal oxides. Due a lack situ studies, reasons such poor performance are not understood. In this study, photoanodes synthesized by aerosol-assisted chemical vapor deposition. The charge carrier dynamics studied...
Ionic carbon nitrides based on poly(heptazine imides) (PHI) represent a vigorously studied class of materials with possible applications in photocatalysis and energy storage. Herein, we study, for the first time, photogenerated charge dynamics highly stable binder-free PHI photoanodes using operando transient photocurrents spectroelectrochemical photoinduced absorption measurements. We discover that light-induced accumulation long-lived trapped electrons within film leads to effective...