Revealing the Role of Catalytic Oxygen Species of Transition Metal Oxide Coated BiVO₄ in Photoelectrochemical Water Splitting

Light harvesting based on photocatalytic generation of chemical fuels, or artificial photosynthesis, has long been sought as a renewable solar energy technology. Solar water splitting within a photoelectrochemical is a typical realization of artificial photosynthesis. Bismuth vanadate (BiVO₄, BVO) is an outstanding photoanode material for photoelectrochemical water splitting, and transition metal oxide coating as cocatalyst is a common strategy to improve the performance of photoanode. Here, we review our recent progress on bismuth vanadate multilayer samples coated by different transition metal oxides as cocatalyst, such as cobalt oxide, iron oxide and nickel oxide, which were synthesized by using pulsed laser deposition (PLD) method. BVO samples with different cocatalyst coatings were then used in both photoelectrochemical chlorine generation, and water splitting reactions. Through different approaches on both samples’ fabrication and during photoelectrochemical reaction, we successfully controlled and regulated the surface oxygen species which were found to have a huge influence on solar energy conversion performance. Detailed mechanistic research and in situ surface characterizations were performed to understand the inherent correlation between different oxygen species and performance, which will have a heuristic effect towards future photoanode material design for both solar water splitting, chlorine generation, and transition metal choosing as cocatalyst.