Fabrication of the ternary heterojunction Cd0.5Zn0.5S@UIO-66@g-C3N4 for enhanced visible-light photocatalytic hydrogen evolution and degradation of organic pollutants

Abstract

A novel ternary heterojunction Cd_0.5Zn_0.5S@UIO-66@g-C₃N₄ (Cd_0.5Zn_0.5S@UCN) has been prepared by the in situ hydrothermal and precipitation approach, which exhibits superior photocatalytic activity for H₂ generation and MO degradation under visible-light irradiation. The Cd_0.5Zn_0.5S@UCN30 composite shows the maximum photocatalytic H₂ production rate (1281.1 μmol h⁻¹ g⁻¹) that is about 32.9 and 2.7 times higher than UIO-66@g-C₃N₄ and pristine Cd_0.5Zn_0.5S, respectively. Besides, the Cd_0.5Zn_0.5S@UCN30 heterojunction indicates the superior degradation efficiency of MO (82%) in 120 min. The improved photocatalytic activity of the Cd_0.5Zn_0.5S@UCN heterostructure can be assigned to its large surface area, enhanced visible-light absorption ability and high-efficiency separation of photogenerated electron–hole pairs, which are proved by the results of photocurrent and EIS analyses. Moreover, the photocatalytic mechanism based on the ternary heterojunction Cd_0.5Zn_0.5S@UCN is discussed and the transfer and separation process of photogenerated electron–hole pairs is also proposed. This work demonstrates that a novel ternary noble-metal-free photocatalytic system could provide a scientific basis for the application in the field of energy production and pollution removal.