Suppressing Water Dissociation via Control of Intrinsic Oxygen Defects for Awakening Solar H2 O-to-H2 O2 Generation.

Abstract

BiVO4 theoretically has a thermodynamic activity trend toward highly selective water oxidative H2 O2 formation, but it is more inclined to generate O2 in practical. The influence of intrinsic oxygen vacancy (Ovac ), especially, on surface reactivity, has never been considered as a possible activity loss mechanism in the synthetic BiVO4 . In this work, it is theoretically and experimentally demonstrated that the intrinsic surface Ovac is responsible for lower H2 O2 evolution activity via promoting water dissociation to form intermediate. Through an annealing process under a V2 O5 rich atmosphere, the surface Ovac can be eliminated that awakens the photoelectrochemical (PEC) water oxidative H2 O2 activity in a NaHCO3 electrolyte, which achieves an average of 58.4%, and increases by up to 4.28 times of the one annealed in air. This work offers a general understanding of catalytic activity loss and may be extended to other photo or electrocatalysts for catalytic selectivity regulation.