Preparation and Properties of CdS/SnO2 Composite Photocatalyst

Abstract

In this paper, CdS/SnO₂ heterojunction photocatalysts with different CdS composite ratios were prepared via a hydrothermal method. Their phase structure, microstructure, specific surface area, surface chemical state, optical properties, and photocatalytic performance were systematically investigated. XRD results indicate that CdS and SnO₂ coexist in the form of a physical heterointerface without lattice doping or distortion. TEM/HRTEM and EDS analyses show that SnO₂ nanoparticles are uniformly dispersed on the surface of the CdS plate-like structure, forming a closely contacted heterointerface that facilitates efficient separation of photogenerated charge carriers. BET tests reveal that the composite possesses a mesoporous structure with a specific surface area of 23.82 m²/g. XPS analysis confirms the existence of a built-in electric field at the heterojunction interface, consistent with type II band alignment characteristics. UV-Vis absorption spectra demonstrate that the introduction of CdS extends the photoresponse range into the visible light region, with the 0.6-CdS/SnO₂ (Cd:Sn = 3:5) sample exhibiting the strongest light absorption capability. PL and TRPL further demonstrate that this sample has the highest photogenerated carrier separation efficiency. Photocatalytic degradation experiments of Rhodamine B (RhB) show that 0.6-CdS/SnO₂ achieves a degradation rate of 93.43% within 70 min, with a reaction rate constant of 3.75×10^-2 min^-1, approximately 4.88 times that of commercial P25 catalyst. Cyclic test results indicate that the composite material possesses good photocatalytic stability and reusability.