Oxygen Vacancies in Shape Controlled Cu2O/Reduced Graphene Oxide/In2O3 Hybrid for Promoted Photocatalytic Water Oxidation and Degradation of Environmental Pollutants.

A novel shape controlled Cu2O/reduced graphene oxide/In2O3 (Cu2O/RGO/In2O3) 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 Cr6+ solutions) compared with pure In2O3 and Cu2O materials. The presence of oxygen vacancies in Cu2O/RGO/In2O3 and the formation of heterojunction between In2O3 and Cu2O 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 Cu2O/RGO/In2O3 hybrid is also attributed to the alignment of band edge, a process that is assisted by different Fermi levels between In2O3 and Cu2O, as well as the charge transfer and distribution onto the graphene sheets, which causes the downshift of VB of In2O3 and the significant increase in its oxidation potential. Additionally, a built-in electric field is generated on the interface of n-type In2O3 and p-type Cu2O, 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.