Graphite-like C3N4 and Graphene Oxide Co-Enhanced the Photocatalytic Activity of ZnO Under Natural Sunlight

To enhance the photocatalytic performance of ZnO, the ZnO/g-C3N4 (ZCN) composite was prepared by ZnO and g-C3N4 under ball milling, and then the ternary graphene oxide (GO)/ZnO/g-C3N4 (GZCN) composite was achieved by using sonicating, stirring, and liquid phase evaporating. The photocatalytic performance was tested under UV light and natural solar light, respectively. The experimental results displayed that the GZCN composite revealed excellent photocatalytic performance under UV light and natural sunlight. When the ratio of ZnO to g-C3N4 is 1:0.2 and the mass fraction of graphene oxide is 0.25% in GZCN composite, the modified ZnO possesses optimal photocatalytic activity under UV light or natural solar light. RhB dye is degraded by 94% within 20 min under UV light, which is 3.41 times that of pure ZnO. Moreover, GZCN can degrade 88% of RhB in 60 min under natural sunlight. The enhancement for photocatalytic activity is attributed to the excellent conductivity of GO and heterojunction interaction between ZnO and g-C3N4, where the special electronic structure of g-C3N4 expands the spectral response range of ZnO and accelerates the transmission of photogenerated electrons and holes.