NiO/g-C3N4 p–n Heterojunctions Wrapped by rGO for the Enhanced CO2 Photocatalytic Reduction

A ternary photocatalyst composed of NiO nanosheets, g-C3N4 nanowires, and monolayer graphene was successfully synthesized and used for the effective photocatalytic reduction of CO2 to CO and CH4. Various techniques were adopted to characterize the morphology, structure, and composition of the NiO/g-C3N4/rGO ternary composite. The significant synergistic interaction of graphene, NiO nanosheets, and g-C3N4 nanowires was confirmed. The NiO/g-C3N4/rGO ternary photocatalyst produced an average CO and CH4 outputs of 22.92 and 5.25 μmol g–1 h–1, respectively, which is 8.3 and 2.9 times greater than those of NiO/g-C3N4. A putative photocatalytic mechanism for CO2 reduction is proposed. It is thought that the construction of p–n heterojunctions and graphene's high-electron conduction capacity aid in photocatalytic CO2 reduction, which is predicted to be used in photocatalysis.