Exploring the Effects of Charge Modulation on the Reaction Energetics of the Oxygen Evolution Reaction in BiVO₄-Based Photocatalysts

Photocatalytic water splitting is a promising and green approach for solar energy storage and hydrogen production. However, its efficiency is limited by the sluggish oxygen evolution reaction (OER), which requires high overpotentials. Bismuth vanadate (BiVO₄) has gained significant attention as a semiconductor photocatalyst due to its favorable properties, including a narrow band gap and chemical stability. Nevertheless, the photoelectric conversion efficiency of the material remains low, and the slow water oxidation kinetics is considered one of the main causes. In this study, density functional theory calculations are performed to investigate the factors that influence the reaction energetics of the OER process on the BiVO₄ surface. Our results reveal a strong correlation between the excess charge provided to BiVO₄ and the reaction energy of the OER steps. Notably, negative charges increase the second and fourth reaction energy, while positive charges have the opposite effect. This behavior is consistent across different modification methods, such as introducing vacancies, doping other elements, and forming heterojunctions. The findings highlight the potential for tuning the reaction energy and overpotential of BiVO₄-based photocatalysts through strategic modifications, advancing their application in efficient solar-driven water splitting.