Chemical reduction-induced surface oxygen vacancies of BiVO₄photoanodes with enhanced photoelectrochemical performance

Bismuth vanadate (BiVO₄) is one of the highly promising photoanodes for photoelectrochemical (PEC) water splitting but suffers from severe carrier recombination and undesirable charge transfer at the semiconductor-electrolyte interface. Herein, we employ an effective surface-engineered sulfite treatment to improve the PEC performance of BiVO₄without illumination. This post-synthetic treatment on BiVO₄photoanodes can substantially enhance the interfacial charge transfer efficiency because of decreased charge carrier recombination arising from both surface oxygen vacancies (O_vac) and surface disordered layers. The as-prepared BiVO₄exhibits a photocurrent density of 2.2 mA cm⁻²at 1.23 Vvs.the reversible hydrogen electrode (RHE) under 1-sun illumination, which is 1.7-times higher than that of pristine BiVO₄. By coating the amorphous FeOOH cocatalyst, the photocurrent density can be further improved to 2.8 mA cm⁻². We demonstrate that the chemical reaction employing a reducing agent with a mild reduction activity can controllably alter the surface states of BiVO₄photoanodes, providing a facile, efficient, and low-cost strategy to achieve high-performance photoelectrodes.