Enhanced Photoelectrochemical Performance of the BiVO4/Zn:BiVO4 Homojunction for Water Oxidation

Abstract Bismuth vanadate is a promising semiconductor for photoelectrochemical (PEC) water oxidation under visible light. Yet its PEC performance is limited by its poor electron‐transfer mobility. In this study we modified the BiVO 4 surface with Zn to address this problem. We used a ZnO coating and etching treatment to dope Zn atoms at the surface of BiVO 4 by replacing the Bi atoms. The surface Zn doping treatment lowered the Fermi level of the outer part of BiVO 4 (surface) and formed a BiVO 4 /Zn:BiVO 4 homojunction with a type II band alignment with the inner part of BiVO 4 (bulk). With this homojunction, the charge transfer process across the depletion region of the BiVO 4 electrode was improved and the surface trapping of photogenerated electrons was avoided, which led to an enhanced PEC performance.