Theoretical Insight into the Mechanism of Photoelectrochemical Oxygen Evolution Reaction on BiVO 4 Anode with Oxygen Vacancy

Oxygen evolution reaction (OER) is the limiting step in a photoelectrochemical (PEC) water splitting process. In this paper, the effect of oxygen vacancies (O vac ) on BiVO 4 photoanode for PEC water splitting is studied using first-principles calculations. The results indicate that the holes transfer at the electrode/electrolyte interface play a defining role in determining the surface catalytic activities, and thus functional characteristics of BiVO 4 photoanode. There are two main reasons behind the enhancement of OER on the surface of the photoanode. First, the V site becomes the active site for PEC water splitting and the number of the active sites are greatly increased by inducing oxygen vacancies. Second, the adsorption energies of H 2 O ads, OH ads, and O ads are higher in the presence of O vac, which implies enhanced hole transfer from the photoanode surface to the electrolyte. The change of Gibbs free energy indicates a high possibility of spontaneous charge transfer to the electrolyte, facilitating OER on surfaces with O vac . These results provide important insights into the roles of O vac on BiVO 4 surface for photocatalytic reactions.