The decisive effect of interface states on the photocatalytic activity of the silver(I) oxide/titanium dioxide heterojunction.

A one-step hydrothermal method was adopted to synthesize the AgO/TiO nanoheterojunction. Its photocatalytic activity was evaluated by degrading methylene blue (MB) aqueous solution under UV and visible light. The MB degradation results showed that the AgO/TiO nanoheterojunction enhances the photocatalytic activity under UV irradiation rather than visible light. X-ray photoelectron spectroscopy (XPS) was performed to detect the electronic structure at the interface of AgO and TiO. The XPS results confirmed that the electronic band structure of the nanoheterojunction was determined by the interface states between the AgO and TiO interface. Thus, the photocatalytic enhancement mechanism can be ascribed to the creation of an additional potential barrier in the conduction band between AgO and TiO, which facilitates the transport of holes from TiO to AgO but inhibits the flow of electrons in the reverse direction unless sufficient potential energy is provided to overcome the additional barrier. Our results have provided a new insight on the role of interface states between the p-n nanojunction in the photocatalytic activity.