Tuning the Surface Wettability of a BiVO₄ Photoanode for Kinetically Modulating Water Oxidative H₂O₂ Accumulation

Photoelectrochemical water splitting into H2 and H2O2 has received increasing attention but suffers from uncontrollable selectivity for water oxidative H2O2 production and low solar conversion efficiency. Herein, we present a N2-treated surface oxygen-vacancy-enriched BiVO4 photoanode (N–Ovac–BVO), which tunes the surface wettability of BVO toward a kinetics-controlled H2O2 production process as well as offers higher charge separation efficiency. As a result, the average Faradaic efficiency (FE) reaches 73.8% from 0.6 to 1.9 V vs RHE with the best FE of 81.2%, up to 4 times higher than that of the BVO photoanode. The H2O2 concentration can accumulate to 4.58 × 10–4 M at 1.6 V vs RHE in 2 h, and the corresponding production rate reaches 11.45 μmol·h–1. This work reveals the importance of the photoanode surface microenvironment and provides effective guidance for photoanode design toward the regulation of competing reactions in an aqueous solution.