Construction of reduced graphene oxide-supported Ag-Cu2O composites with hierarchical structures for enhanced photocatalytic activities and recyclability

Ternary spherical Ag-Cu2O/reduced graphene oxide (rGO) nanohybrids with excellent hierarchical structures are developed through a simple one-pot, two-stage reduction synthetic route at room temperature without any surfactant. In the resultant complex heterostructures, both Ag and rGO are in direct contact with Cu2O, and Ag nanocrystals are mainly deposited on the surface of Cu2O spheres. The resultant ternary spherical Ag-Cu2O/rGO composite exhibits excellent photocatalytic activity in photocatalytic degradation of methyl orange (MO) under visible light irradiation, which is much higher than that of either the single component (Cu2O) or two component systems (spherical Cu2O/rGO and Ag-Cu2O). In particular, the resultant ternary composites possess excellent stability and extend the light absorption range. The PL spectrum results have demonstrated that not only Ag but also rGO could capture the photogenerated electrons from Cu2O, thus leading to effective separation of electrons and holes. In particular, it is found that the direct junction and interaction between Ag and Cu2O in the ternary composites are more beneficial for charge transportation than the direct contact between Ag and rGO (labeled as sample Ag-rGO-Cu2O), and thereby the resultant Ag-Cu2O/rGO composites with such complex heterostructures exhibit a better photoactivity than the sample Ag-rGO-Cu2O. This work provides an insight into designing and synthesizing new Cu2O-based hybrid materials for effectively improving the photocatalytic performance.