Preparation,Modification And Photocatalytic Property Of Zn_0.1Sn_0.1Cd_0.8S_x For Cr（Ⅵ） And 4-Nitrophenol

Nanostructured metal sulfides mainly include one-component sulfides（MoS₂,SnS₂,Bi₂S₃,etc.）and two-component sulfides（Cu₃SnS₄,CuGaS₂,CdIn₂S₄,etc.）.These metal sulfides have good optical response to visible light,but their shortcomings are low charge separation efficiency,rapid photo-induced charges recombination and photoetching.In recent years,ternary metal sulfides have attracted huge attention due to their excellent redox reversibility and high electron conductivity.In this study,a series of ternary metal sulfides Zn_0.1Sn_0.1Cd_0.8S_x（ZSCS）with sulfur vacancies were synthesized through simple hydrothermal method.Taking Cr（Ⅵ）as the target pollutant,the effects of sulfide content,catalyst dosage,pH value and initial Cr（Ⅵ）concentration on the photocatalytic efficiency of Cr（Ⅵ）reduction were studied.X-ray powder diffraction（XRD）,X-ray photoelectron spectroscopy（XPS）,transmission electron microscopy（TEM）and electron spin resonance（ESR）and other characterization methods were used to explore the microstructure of the catalyst,and the mechanism of photocatalytic reduction of Cr（Ⅵ）was deeply analyzed.The results indicated that the catalyst could reduce 90%Cr（Ⅵ）within 3 min under visible light irradiation.Singlet oxygen（¹O₂）,electrons（e^-）and superoxide radicals(O₂^·-)were the active species involved in the reduction process.The enhanced photocatalytic reduction performance was mainly attributed to the phase transformation and sulfur vacancies number.Using ZSCS as matrix and HAu Cl₄?4H₂O as Au source,a series of ZSCS loaded AuNPs composites were synthesized through photodeposition,which was used to photothermal catalytic reduction of 4-NP through synergy of visible light and NaBH₄ reduction.The microstructures of the catalysts were characterized by XRD、TEM、XPS、EPR、ESR,etc.The experimental parameters,including catalyst dosage,pollutant concentration,pH value and NaBH₄ concentration were optimized.The main active species involved in the reduction process were explored.The results showed that the reduction efficiency of 4-NP reached over 90%in the water system with 2 mL 0.3 mol?L^–1 NaBH₄ under visible light irradiation for 20 min.The enrichment of surface charge on AuNPs and the formation of Au-H bond were mainly responsible for the enhanced reduction efficiency.