Water adsorption onto Y and V sites at the surface of the YVO_4photocatalystand related electronic properties

摘要

The dynamics of water molecules and the adsorption properties at the V and Y sites on the surfaceof the photocatalyst YVO_4have been investigated by first principles molecular dynamics. Thissystem has shown an excellent performance in the production of both hydrogen and oxygen in theultraviolet region. Yet, its catalytic properties, related to the electronic structure, are poorlyunderstood. Here we show that imperfectly oxygen coordinated V sites (i.e., not fourfold oxygencoordinated vanadium but threefold oxygen coordinated vanadium) exposed on the catalyst surfaceplay a central role in the dissociation of water molecules. By simulating the H_20 adsorption processand by performing an analysis of the electronic structure of the unoccupied orbitals correspondingto the lowest unoccupied energy level of the system, we can infer that the dissociation of water atthese imperfectly oxygen coordinated V sites can promote the proton reduction and is expected totrigger the H_2generation.