Photocatalytic O₂ evolution with the visible-light-driven photocatalysts M₃V₂O₈ (M = Mg, Zn)

Photocatalytic O₂ evolution from aqueous AgNO₃ solution with M₃V₂O₈(M = Mg, Zn) was carried out under visible light irradiation. The M₃V₂O₈powder samples synthesized by a solid-state reaction method were characterized by X-ray diffraction and UV-Vis diffuse reflectance spectroscopy. M₃V₂O₈had similar crystal structures and band gaps. However, the photocatalytic activity of O₂evolution for Zn₃V₂O₈was much higher than that for Mg₃V₂O₈. It was suggested that the Zn-3d orbital hybridized with the O-2p orbital in constructing the valence band of Zn₃V₂O₈, whereas there was no such hybridization involving in the valence band of Mg₃V₂O₈. The different photocatalytic properties could be ascribed to their different electronic structures.