Preparation and Properties of ZnS/SnO2 Composite Photocatalyst

Abstract

In this paper, ZnS/SnO₂ composite photocatalysts with different molar ratios were prepared by a two-step hydrothermal method. The influence of ZnS composite ratio on the material structure, morphology, optical properties and photocatalytic performance was systematically investigated. XRD and XPS results indicate that the SnO precursor is completely transformed into rutile SnO₂ during the hydrothermal process, and ZnS is composited on the SnO₂ surface in the form of cubic sphalerite, forming a heterostructure rather than a solid solution. SEM, TEM and EDS show that the composite exhibits a porous nano-aggregate morphology with a close heterojunction interface formed between ZnS and SnO₂. BET analysis reveals that the material possesses a mesoporous structure with a specific surface area of 14.36 m²/g. UV-vis absorption spectra show that the absorption edge of the composite is red-shifted, extending the photoresponse range to the visible region. The photocatalytic degradation experiments of rhodamine B (RhB) demonstrate that the composite with a ZnS ratio of 80% (0.8-ZnS/SnO₂) exhibits the best performance, achieving a degradation rate of 93.52% within 70 min and a reaction rate constant of 3.74×10^-2 min^-1, which is about 5 times that of commercial P25. Cyclic catalytic tests prove that the composite has good reusability and photostability. This study provides a feasible synthesis strategy and structural optimization basis for constructing efficient type II heterojunction photocatalysts.