Hangjuan Ren

University of Oxford | OX · Department of Chemistry

Electrochemical carbon dioxide reduction is a potential pathway for sustainable production of fuels and chemicals. However, the detailed catalytic mechanism in cells using high-current gas diffusion electrodes remains uncertain. Here we use proton-transfer-reaction time-of-flight mass spectrometry (PTR–TOF–MS) to perform operando analysis of interm...

Bismuth-based metal oxide compounds are promising candidates as novel photocatalysts for environmental remediation. However, their low quantum efficiencies and rapid electron-hole recombination times have hindered their uptake for photocatalytic applications. The present work reports an investigation of the effects of variable Bi/Ti ratio during hy...

There is considerable interest in the pH-dependent switchable biocatalytic properties of cerium oxide nanoparticles (CeNPs) in biomedicine, where these materials exhibit beneficial antioxidant activity against reactive oxygen species at neutral and basic physiological pH but cytotoxic prooxidant activity at acidic pathological pH. Oxygen vacancies...

Nickel-based catalysts are most commonly used in industrial alkaline water electrolysis. However, it remains a great challenge to address the sluggish reaction kinetics and severe deactivation problems of hydrogen evolution reaction (HER). Here, we show a Cu-doped Ni catalyst implanted with Ni-O-VOx sites (Ni(Cu)VOx) for alkaline HER. The optimal N...

Heterostructured catalysts with unique interfaces and properties endow distinct advantages for many electrochemical reactions. Herein, a phosphine (PH3) vapor-assisted phase and structure engineering strategy is developed for the controllable conversion of non-active NiTe into a heterostructured active Ni2P/NiTe2 catalyst for alkaline hydrogen evol...

Bridging heteroatoms on the surface of electrocatalysts, aiming to modify the surface atomic and electronic configuration, is of prime importance to improve the electrocatalytic performance. The present work establishes Co-P bridging on the surface of Co3O4 via a vapor-assisted treatment in a controlled molar ratio of P/Co (0.08 ∼ 0.66). The oxygen...

Electrocatalytic activities of electrodes for water splitting generally are assessed in terms of current density normalisation on the basis of geometric area. However, this approach does not involve the effects of surface microstructure which often is rough. The present work examines this disagreement through the electrochemical characterisation of...

Facet engineering is a new method of materials design with considerable potential for many technological applications. The present work uses DFT calculations to understand how this strategy can be used to accelerate the silanization of tetraethyl orthosilicate (TEOS) on the surface of ceria (CeO2), which is a key technology in biomedical and other...

Conductive metal oxides represent a new category of functional material with vital importance for many modern applications. The present work introduces a new conductive metal oxide V13O16, which is synthesized via a simplified photoelectrochemical procedure and decorated onto the semiconducting photocatalyst BiVO4 in controlled mass percentages ran...

The present work reports data for the mineralogical, nanostructural, optical, and photocatalytic properties of Cr-doped, V-doped, and Cr/V- codoped TiO2 nanoparticles in terms of the effects of doping level and associated particle size on the photocatalytic performance. The photocatalytic performance of doped TiO2 is dependent on only the particle...

Nickel‐heteroatoms bridge sites are important reaction descriptors for many catalytic and electrochemical processes. Herein we report the controllable surface modification of nickel‐nitrogen (Ni‐N) bridge sites on metallic Ni particles via a simplified vapor‐assisted treatment approach. X‐ray absorption spectroscopy (XAS) and Operando Raman spectro...

Nickel‐heteroatoms bridge sites are important reaction descriptors for many catalytic and electrochemical processes. Herein we report the controllable surface modification of nickel‐nitrogen (Ni‐N) bridge sites on metallic Ni particles via a simplified vapor‐assisted treatment approach. X‐ray absorption spectroscopy (XAS) and Operando Raman spectro...

In this work, a surface sulfurization strategy is utilized to construct Co3O4@CoSx heterogeneous catalysts with a highly efficient activity towards oxygen evolution reaction (OER), and the enhanced catalytic activity is dependent on the degree of surface sulfurization. It is found that forming an amorphous CoSx on the Co3O4 surface through the surf...

Hematite (α-Fe2O3) is one of the most promising photoanode materials for solar-to-hydrogen (STH) energy conversion by photoelectrochemical (PEC) water splitting. However, the practical application of hematite in PEC water splitting is severely hindered by the intrinsically low charge separation efficiency and sluggish water oxidation kinetics. Here...

Sn-doped anatase hollow spheres were fabricated using a template method involving polystyrene spheres as core and anatase coating as shell. The synthesis route included the preparation of PS spheres, followed by their coating by Sn-doped TiO2 sol-gel precursor and subsequent removal of the PS cores by pyrolysis and recrystallization at 500°C for 2h...

The present work reports data for the mineralogical and chemical properties of anatase thin films individually doped or codoped with chromium and vanadium, fabricated by sol-gel spin coating on glass substrates and annealing at 450 °C for 2 h. X-ray photoelectron spectroscopy data indicated the presence of Ti(4+), Ti(3+), Cr(3+), and possibly Cr(4+...

We present a novel and notably simple approach to fabricate BN nanoplates in large scale employing ammonia borane as a single-source precursor. The structure and chemical composition of the assynthesized products are extensively characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron micro...