Ag3PO4 Oxygen Evolution Photocatalyst Employing Synergistic Action of Ag/AgBr Nanoparticles and Graphene Sheets

A graphene-supported Ag3PO4/Ag/AgBr water oxidation photocatalyst was prepared by a photoassisted deposition-precipitation reaction, followed by a hydrothermal treatment. The composite photocatalyst exhibits double the O-2-production activity than that of bare Ag3PO4 under visible light irradiation. Moreover, it exhibits enhanced activity in comparison to unsupported Ag3PO4/Ag/AgBr, to graphene-supported bare Ag3PO4 powder as well as to Ag/AgBr powder. This increase in activity is attributed to a combination of depletion of the conduction band of the as-synthesized n-doped Ag3PO4 material and a downshift of the Ag3PO4 valence band due to the pinning of its conduction band at the silver Fermi level, a process that is assisted by charge transfer and distribution onto the graphene support.