Photoelectrochemical (PEC) water splitting is a promising green technique for renewable hydrogen production. In order to build a practical PEC system, it is of great importance to develop efficient photoanodes. BiVO4 was identified as the most promising photoanode material due to its narrow band gap and favorable band positions for hydrogen and oxygen evolution. Nevertheless BiVO4 has limitations of low carrier mobility (4 × 10−2 cm2·V−1s−1) and short hole diffusion length (<100 nm) as photoanode, resulting in unsatisfactory photocurrent density (<1 mA cm−2 at 1.23 V vs. RHE in neutral medium under AM 1.5 G illumination). Hence, it is necessary to investigate a number of methods to improve the PEC performance of BiVO4.
It has been proposed and studied to insert a new layer between BiVO4 and fluorine-doped tin oxide (FTO) can improve carrier separation efficiency. Among them BiVO4/WHERE3 is an established type II heterojunction. The surface and deposition of an oxygen evolution co-catalyst (OEC) layer can improve water oxidation kinetics. But most WO3 Arrays on FTO electrodes exhibit small array gaps (<60 nm) that are not conducive to uniform BiVO loading4 Nanoparticles with a size of more than 80 nm. In addition, the top layer is made of BiVO4 is WO coated on the underside3 Layer to form a double-layer heterojunction, which has a small contact area and inevitable charge recombination in the bulk and at the boundary of BiVO4 particles.
Recently, a research team led by Prof Junwang Tang from University College London, UK and Hai-Ying Jiang from Northwest University, China, WO fabricated3 Nanobowl arrays based on monolayer colloidal crystals (MCCs) to build a highly customized BiVO4/WHERE3 Heterojunction with BiVO4. In this new design is the small BiVO4 Nanoparticles (< 90nm) are perfectly deposited on the bottom layer of WO3 Large inner diameter nanobowl of 920 nm. The size of BiVO4 is smaller than its hole diffusion length (~100 nm), which ensures that holes are efficiently transferred to its surface. Meanwhile, a highly ordered monolayer WO3NB array was chosen to minimize WO3 Defects at grain boundaries, reducing interfacial resistance with FTO and increasing contact area with BiVO4 nanoparticles. Then there is the highly tuned BiVO4/WHERE3 Interface can also improve the charge separation of BiVO4, which plays an important role in the PEC process. In addition, to improve the kinetics of water oxidation, the authors loaded an OEC layer on the BiVO4/WHERE3NB heterojunction photoanode that produced about 5 times higher photocurrent and IPCE than pure BiVO4 under a sunlight condition. The results were published in Chinese Journal of Catalysis (https://doi.org/10.1016/S1872-2067(21)63927-X).
About the journal
Chinese Journal of Catalysis is co-sponsored by the Dalian Institute of Chemical Physics, the Chinese Academy of Sciences and the Chinese Chemical Society and is currently published by the Elsevier group. This monthly journal publishes updated articles from original manuscripts and carefully reviewed manuscripts, covering all areas of catalysis, in English. The journal publishes Reviews, Accounts, Communications, Articles, Highlights, Perspectives and Viewpoints of high scientific value that contribute to the understanding and definition of new concepts in both fundamental questions and practical applications of catalysis. Chinese Journal of Catalysis is one of the two top journals in applied chemistry with a current SCI impact factor of 12.92. The editors-in-chief are Profs. Can Li and Tao Zhang.
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