Preparation And Photocatalytic Performance Of SnS₂ And Its Composite Material

Tin disulfide（SnS₂）is a layered metal sulfide of cadmium iodide（CdI₂）type crystal structure.It has a suitable band gap（2.2 e V）and excellent photoelectric activity,making it have excellent application value in the field of photoelectric and photocatalysis.However,SnS₂is also constrained by the high recombination rate of photogenerated electron-hole Pair,light sources utilization rate,and insufficient surface active sites,which limit the application and development of SnS₂ in the field of photocatalysis.Therefore,it is of great significance to study the modification of SnS₂,adjust its morphology,energy band structure,and catalytic properties,and synthesize SnS₂ composites with excellent photocatalytic activity,so as to promote the application of SnS₂ in the field of photocatalysis.This study uses SnS₂ synthesized by hydrothermal method as the matrix material,graphene oxide（GO）,graphite phase carbon nitride（g-C₃N₄）,polyvinyl pyrrolidone（PVP）,sodium dodecyl sulfate(C₁₂H₂₅SO₄Na,K12),and citric acid monohydrate（C₆H₈O₇·H₂O,CA）for the modification SnS₂。The morphology,structure,and absorption sidebands of the composite products were analyzed by X-ray powder diffraction（XRD）,Raman spectroscopy（Roman）,Fourier transform infrared spectroscopy（FT-IR）Ultraviolet-visible diffuse reflectance（UV-vis）,high-resolution transmission electron microscopy（HRTEM）,electrochemical impedance spectroscopy（EIS）,fluorescence spectroscopy（PL）,specific surface area measurement（BET）,electron paramagnetic resonance（EPR）,etc.Photocatalytic degradation of methylene blue,rhodamine B,and crystal violet simulated pollutants was carried out.The effects of GO,g-C₃N₄,PVP,K12,and CA on the morphology,structure,and catalytic performance of tin disulfide were studied,as well as the morphology,structure,photocatalytic performance,catalytic kinetics,and catalytic mechanism of tin disulfide composite materials were investigated.（1）SnCl₂ was synthesized by hydrothermal method with Tin tetrachloride pentahydrate（SnCl₄·5H₂O）as the tin source and thioacetamide（C₂H₅NS）as the sulfur source,and then 5wt%,10wt%,and 15wt%GO and g-C₃N₄ were compounded by hydrothermal method,grinding method,and liquid phase method respectively to obtain SnS₂/GO and SnS₂/g-C₃N₄ nanocomposite photocatalytic materials.By characterizing and analyzing the composite product.It was found that the wavelength range of light absorbed increased,the specific surface area increased,the band gap decreased,and the fluorescence intensity and resistance decreased when SnS₂was combined with GO and g-C₃N₄.Thus,the problems of high recombination rate of SnS₂ photogenerated electron hole pairs,poor utilization of light sources and insufficient surface active site are solved.The degradation rate of methylene blue by 15 mg of G:SnS₂/10wt%GO reached 92%at80 min of photocatalytic reaction,and the L:SnS₂/5wt%g-C₃N₄ reached 90%at 140 min of photoreaction.Compared with SnS₂,the composite photocatalysts have a better separation effect of photo-generated electron-hole pairs and light source utilization rate,more efficient catalytic effect,and cyclic stability,and the catalytic process conforms to the Langmuir-Hinshelwood first-order kinetic model.The active substance in the photocatalytic degradation of methylene blue using SnS₂/GO composite photocatalyst is mainly photogenerated electrons（e^-）.The main catalytic free radicals for the photocatalytic degradation of methylene blue in SnS₂/g-C₃N₄ composite materials are e-and·OH.（2）SnS₂/PVP,SnS₂/K12,and SnS₂/CA photocatalysts were synthesized by hydrothermal method using tin tetrachloride pentahydrate as the tin source,and thioacetamide as the sulfur source by adding 2.5%,5%,and 7.5%molar ratios of PVP,K12,and CA,respectively.After characterization and analysis,the product has uniform grain size,good dispersion,and high crystallinity.PVP,K12,and CA can increase the wavelength range of absorbing light absorption and decrease the resistance of SnS₂.The photocatalytic performance of SnS₂/PVP,SnS₂/K12,and SnS₂/CA photocatalyst is better than SnS₂.