One-Step Fabrication of CdS/Ag2S Heterojunction Composites and Its Enhanced Visible-Light Photocatalytic Degradation Performance

The design and construction of Ag 2 S heterostructures capable of significantly separating photocarriers is a significant challenge in photocatalysis. In this study, CdS/Ag 2 S heterojunction composite photocatalyst is fabricated through a simple one-step hydrothermal method. The composite structure is characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and UV-visible diffuse reflection spectroscopy. Under visible light irradiation, the photocatalytic activity of the sample is evaluated by degradation of methyl orange. The photoelectric chemical performance of the CdS nanoparticles modified by Ag 2 S is closely related to the ratio of Cd/Ag cation. The experimental results show that the sample ACS-2 (CdS-Ag 2 S = 1:1) composite has higher charge transfer/separation efficiency and longer carrier life. The degradation efficiency reaches 74.4% within 30 min, and the degradation rate constant is 0.047 min −1 . After four cycles, the degradation efficiency of the catalyst only decreases slightly, indicating that the CdS/Ag 2 S catalyst has good stability and repeatability. Meanwhile, the study of the photocatalytic mechanism shows that •O 1 − is the primary active substance in the catalytic process, and h + and •OH play a secondary role. This work provides a great significance for constructing efficient Ag 2 S-based heterojunction photocatalyst systems.