Bismuth Vacancies Induced Lattice Strain in BiVO₄ Photoanodes Boosting Charge Separation For Water Oxidation

Abstract

Photoelectrochemical (PEC) water splitting is a promising technology for green hydrogen production. However, severe charge recombination in the photoelectrode materials is one of the key obstacles to achieving high performance. Herein, a BiVO₄ photoanode with lattice strain (Str‐BVO) is constructed by generating Bi vacancies to promote charge separation in the bulk. The optimized Str‐BVO photoanode achieves a photocurrent density of 6.20 mA cm⁻2 at 1.23 V versus the reversible hydrogen electrode under AM 1.5 G illumination, with an impressive charge separation efficiency close to 100%. Systematical experiments and density functional theory reveal that the surface Bi vacancies induced strain causes the distortion of a small number of VO4 tetrahedra, which increases the antibonding state energy of most normal VO4 tetrahedra and creates more electronic vacancy states, thereby significantly promoting electron–hole separation. By surface loading with a FeNiOx co‐catalyst, the photoanode exhibits excellent PEC water‐splitting performance and stability.