Suppressing Water Dissociation via Control of Intrinsic Oxygen Defects for Awakening Solar H2O-to-H2O2 Generation

BiVO4 theoretically has a thermodynamic activity trend toward highly selective water oxidative H2O2 formation, but it is more inclined to generate O-2 in practical. The influence of intrinsic oxygen vacancy (O-vac), 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 O-vac is responsible for lower H2O2 evolution activity via promoting water dissociation to form intermediate. Through an annealing process under a V2O5 rich atmosphere, the surface O-vac can be eliminated that awakens the photoelectrochemical (PEC) water oxidative H2O2 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.

Automated summary

This study demonstrates that intrinsic surface oxygen vacancies promote water dissociation to form intermediates, resulting in decreased H2O2 evolution activity in BiVO4. By eliminating these vacancies through a specific annealing process, the photoelectrochemical water oxidative H2O2 activity can be enhanced, offering a new approach for regulating selectivity in other catalysts.