Understanding the Roles of NiOx in Enhancing the Photoelectrochemical Performance of BiVO4 Photoanodes for Solar Water Splitting

Solar water oxidation is considered as one of the most promising methods to utilize solar energy efficiently, and bismuth vanadate BiVO4 is a potential photoanode. Catalyst loading on BiVO4 is often used to tackle the limitations of charge recombination and sluggish kinetics. In this study, amorphous nickel oxide NiOx is loaded on BiVO4 by photochemical metal organic deposition method. The resulting NiOx Mo BiVO4 photoanodes demonstrates a 2 fold improvement of photocurrent density of 2.44 mA cm 2 at 1.23 V vs. RHE as compared with uncatalyzed samples. After NiOx modification, both the charge separation and the charge transfer efficiency significantly increase across the entire potential range. It is further elucidated by open circuit photovoltage OCP , time resolved microwave conductivity TRMC and rapid scan voltammetry RSV measurements that NiOx modification introduces larger band bending and promotes efficient charge transfer on the surface of BiVO4. Our work provides insights into designing excellent BiVO4 catalyst assemblies using a simple surface modification route for efficient solar water oxidatio