Preparation of ternary metal Sulfide/g-C3N4 heterojunction catalysts and their photocatalytic activity under visible light

Abstract

A novel Zn-Mo-CdS/g-C3N4 heterojunction photocatalyst was prepared by hydrothermal posttreatment using dicyandiamide, zinc acetate, ammonium molybdate, cadmium acetate, and sodium sulfide as raw materials. X-ray diffraction (XRD), ultraviolet-visible (UV-Vis), inductively coupled plasma atomic emission (ICP-AES), electrochemical impedance spectroscopy (EIS), and X-ray photoelectron spectroscopy (XPS) were used to characterize the prepared catalysts. The results indicate that heterojunctions are formed across the g-C3N4/Zn-Mo-CdS interface, which promotes interfacial charge transfer and inhibits the recombination of electrons and holes. The activities of as-prepared catalysts were tested through the photocatalytic degradation of Rhodamine B (RhB) under visible light. The results show that the Zn-Mo-CdS/g-C3N4 heterojunction photocatalyst clearly displayed increased activity compared with single g-C3N4 and Zn-Mo-CdS. At an optimal g-C3N4 mass fraction of 20%, the as-prepared heterojunction photocatalyst displayed the highest rate constant under visible light, which was 30 and 10 times of single g-C3N4 and Zn-Mo-CdS, respectively. Not only Zn-Mo-CdS, but also Mo-Ni-CdS and Ni-Sn-CdS can form heterojunctions with g-C3N4 to promote the rate of separation of electrons and holes and improve photocatalytic activity.