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.

Keywords:

• Photocatalysis
• g-C₃N₄
• ZnO
• Reactive brilliant blue

Acknowledgements

This study was supported by the National Natural Science Foundation of China (grant no. 21243005, 21476033), the Science and Technology Foundation of Liaoning of China (grant no. 201102111), the Program for Key Science and Technology Platform in Universities of Liaoning Province, the Program for Liaoning Excellent Talents in University (grant no. LR2014013), and the Science and Technology Public-Benefit Foundation of Liaoning of China (grant no. [2011] 49).