Oxygen Vacancies in Shape Controlled CuO/Reduced Graphene Oxide/InO Hybrid for Promoted Photocatalytic Water Oxidation and Degradation of Environmental Pollutants.

A novel shape controlled CuO/reduced graphene oxide/InO (CuO/RGO/InO) hybrid with abundant oxygen vacancies was prepared by a facile, surfactant-free method. The hybrid photocatalyst exhibits an increased photocatalytic activity in water oxidation and degradation of environmental pollutants (methylene blue and Cr solutions) compared with pure InO and CuO materials. The presence of oxygen vacancies in CuO/RGO/InO and the formation of heterojunction between InO and CuO induce extra diffusive electronic states above the valence band (VB) edge and reduce the band gap of the hybrid consequently. Besides, the increased activity of CuO/RGO/InO hybrid is also attributed to the alignment of band edge, a process that is assisted by different Fermi levels between InO and CuO, as well as the charge transfer and distribution onto the graphene sheets, which causes the downshift of VB of InO and the significant increase in its oxidation potential. Additionally, a built-in electric field is generated on the interface of n-type InO and p-type CuO, suppressing the recombination of photoinduced electron-hole pairs and allowing the photogenerated electrons and holes to participate in the reduction and oxidation reactions for oxidizing water molecules and pollutants more efficiently.