The free energy surface of the oxygen evolution reaction at BiVO₄-water interfaces

Harvesting energy from sunlight through photocatalytic water splitting is a key area of research that attracts significant global interest. The primary challenge in this process is the oxygen evolution reaction (OER), which requires a detailed investigation of the kinetic barriers during the transfer of photogenerated holes from photocatalysts to adsorbed water molecules. Traditional methods, such as simulating free energies with QM/MM schemes or DFT molecular dynamics, face convergence issues on the picosecond timescale. Moreover, static geometry relaxation or NEB calculations fail to account for the dynamic nature of interfaces, leading to uncertain barrier estimations. In this study, we utilize machine learning potentials to drive the free energy surface calculation for hole transfer at BiVO₄-water interfaces. This method enables us to identify the kinetic barriers of the OER at the interface, including the impact of water dynamics, providing crucial insights into the OER bottleneck.