Preparation of g-C3N4/ZnO composites and their enhanced photocatalytic activity

Abstract

In this manuscript, g-C3N4/ZnO composite photocatalysts with various loadings of g-C3N4 were synthesised by a facile thermal decomposition method. The obtained g-C3N4/ZnO composites were characterised by X-ray diffraction, SEM, photoluminescence spectroscopy, UV–vis and X-ray photoelectron spectroscopy. It is discovered that the introduction of g-C3N4 did not change the morphology and crystal structure of g-C3N4/ZnO composites but enhanced their light absorption in the visible region and promoted the charge separation of photoexcitated electron–hole pairs. As compared to ZnO, the Zn2p peak of the g-C3N4/ZnO composite showed an obvious shift to higher binding energy, implying the existence of a synergistic effect between g-C3N4 and ZnO. Furthermore, the introduction of g-C3N4 also increased the amount of hydroxyl groups where the surface hydroxyl groups can be trapped in the photogenerated holes to form hydroxyl radicals, and improved the photocatalytic efficiency. The photodegradation of reactive brilliant blue (KN-R) showed that the g-C3N4/ZnO composites possess better photocatalytic activity than that of g-C3N4 and ZnO under sunlight irradiation.