Design of graphitic carbon nitride supported Ag–Cu2O composites with hierarchical structures for enhanced photocatalytic properties

A novel ternary photocatalytic nanocomposite, Ag–Cu 2 O/C 3 N 4 , has been successfully synthesized via a facile two-step reduction procedure at room temperature, wherein Ag nanoparticles are directly growing on the surface of Cu 2 O supported by C 3 N 4 nanosheets. The resulting ternary Ag–Cu 2 O/C 3 N 4 photocatalyst exhibits enhanced photocatalytic activity towards methyl orange (MO) degradation compared with its counterparts (Cu 2 O, spherical Ag–Cu 2 O and Cu 2 O/C 3 N 4 ), demonstrating a removal rate of MO up to 95.7% within 30 min. The enhanced photocatalytic activity can be ascribed to the following factors: (1) the surface plasmon resonance effect of Ag nanoparticles broadening the visible light response of Cu 2 O; (2) the introduction of C 3 N 4 functioning not only as a fast electron delivery but also a fine stabilizer to prevent the Ag–Cu 2 O composite from agglomeration. Mechanism studies reveal that MO is cracked into smaller fragments and the h + is the main reactive species participating in the photocatalytic process. Moreover, the Ag–Cu 2 O/C 3 N 4 photocatalyst also shows high photodegradation ability for another two representative azo dyes, acid orange II and congo red. This study demonstrates the potential of Ag–Cu 2 O/C 3 N 4 in the degradation of azo dyes and also provides a guide to design of Cu 2 O-based ternary photocatalysts for further wastewater remediation.