Theoretical Insight into the Mechanism of Photoelectrochemical Oxygen Evolution Reaction on BiVO₄ Anode with Oxygen Vacancy

Abstract

Oxygen evolution reaction (OER) is the limiting step in a photoelectrochemical (PEC) water splitting process. In this paper, the effect of oxygen vacancies (Ovac) on BiVO4 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 BiVO4 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 H2Oads, OHads, and Oads are higher in the presence of Ovac, 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 Ovac. These results provide important insights into the roles of Ovac on BiVO4 surface for photocatalytic reactions.

A DFT-Based Model on the Adsorption Behavior of H2O, H+, Cl−, and OH− on Clean and Cr-Doped Fe(110) Planes

“…In DFT calculations, the Generalized Gradient Approximation (GGA) in the form of the Perdew-Burke-Ernzerhof (PBE) method was used for the exchange-correlation function [13][14][15][16][17]. The spin value was set to be unrestricted, and the formal spin was expressed as the initial value [18].…”

Water oxidation catalysed by quantum-sized BiVO4

“…In a recent work, Hu et al also considered the mechanism of water oxidation on the (010) facet of BiVO4 and the role of oxygen vacancies, which facilitated the reaction by decreasing the activation energy barriers of the catalytic reactions. 20 Since the use of nanoparticulate photocatalysts has been proven to be a strong strategy to dramatically improve solar-tofuel conversion efficiencies, 21,22 understanding the role of size reduction is of fundamental importance in the development of efficient BiVO4 quantum-sized water-splitting photocatalysts. Herein, we report a comprehensive theoretical investigation of the structural and optical properties of a model bismuth vanadate nanoparticle, (BiVO4)4, and a quantification of the initial steps (1-3) in the water-splitting reaction by means of a combination of density functional theory (DFT) methods (ab initio molecular dynamics, transition state searching, timedependent DFT).…”

Deep Eutectic Solvent‐Assisted Synthesis of Ternary Heterojunctions for the Oxygen Evolution Reaction and Photocatalysis

“…From this polarization curve, pure BOC/BVO had poor catalytic activity in the dark and with light irradiation for OER, whereas BOC/BVO/g‐CN‐15 exhibited excellent OER activity. The oxidation of photocatalysts can be observed at 1.6 V under light compared with dark conditions because there is the possibility for photooxidation of V 4+ to V 5+ and the photooxidation of Bi 3+ to Bi 5+ under light irradiation, compared with dark conditions . A V atom on the perfect surface cannot be further oxidized because its highest valence is +5, so the Bi is the active site.…”

“…Figure c indicates the flat band potential is approximately −1.4 V in the dark and −1.07 V in light versus Ag/AgCl, considering the flat band potential in light is equivalent to −0.82 eV (vs. NHE). Understanding the OER mechanism on heterogeneous photocatalysts requires detailed knowledge of electrode/electrolyte interface reactions, and how reaction intermediates interact with the photocatalyst surface . Describing the exact OER mechanistic pathway is very difficult.…”