Chemical reduction-induced surface oxygen vacancies of BiVO ₄ photoanodes with enhanced photoelectrochemical performance

Abstract

A facile chemical treatment employing a reducing agent sodium sulfite with a mild reduction activity is used to alter the surface states of BiVO ₄ photoanodes. The sulfite-treated BiVO ₄ (S-BiVO ₄) exhibits an enhanced photoelectrochemical performance.

Abstract

Bismuth vanadate (BiVO ₄) 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 BiVO ₄ without illumination. This post-synthetic treatment on BiVO ₄ photoanodes 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 BiVO ₄ exhibits a photocurrent density of 2.2 mA cm ⁻² at 1.23 V vs. the reversible hydrogen electrode (RHE) under 1-sun illumination, which is 1.7-times higher than that of pristine BiVO ₄. 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 BiVO ₄ photoanodes, providing a facile, efficient, and low-cost strategy to achieve high-performance photoelectrodes.