Preparation And Photocatalytic Activity Of Tin Disulfide Based Material

Semiconductor photocatalysis is considered to be promising green technologies due to its low energy consumption,low cost,no secondary pollution and effective use of solar energy.It can be used to solve the environmental and energy problems human beings faced.The development of photocatalysts that can effectively utilize sunlight and possess high photocatalytic reaction activity is the key to achieve their commercial applications.In recent years,the methods that include controlling the morphology and size of photocatalysts,doping metal elements,compositing graphene materials,loading precious metals,etc.are applied to improve the photocatalytic activity,which has attracted wide attention of researchers and become hot spot in the research field of semiconductor photocatalysis.SnS₂ is a potentially efficient photocatalyst because of its non-toxic,inexpensive and abundant source and good response to visible light.In this paper,SnS₂ quantum dots,nanosheets and nanoflowers and Ce doped SnS₂ nanoflowers were successfully prepared by hydrothermal method.The effects of microstructure,morphology,band structure,optical properties and electrochemical properties of the materials on the photocatalytic performance were systematically studied.The main contents of this paper are shown as follows:?1?Study on photocatalytic reduction of Cr???by Ce doped tin disulfide.Ce doped tin disulfide were prepared using citrate,tin tetrachloride pentahydrate,thiourea and cerium nitrate hexahydrate as raw materials by one-step hydrothermal method.X-ray diffraction,scanning electron microscopy and X-ray energy spectrum were characterized to prove the existence of cerium doping.The rose-like structure of the sample and its spiral growth process were found.Diffuse reflectance spectroscopy and electrochemical testing are examined to elaborate the effects of cerium doping on the light absorption,band gap,conduction band potential and photo-generated carrier separation efficiency of tin disulfide.The photocatalytic reduction performance of the sample was evaluated by using a certain concentration of Cr???solution as a model pollutant.The results show that the photoreduction ability of Ce-doped tin disulfide is related to the concentration of Ce concentration,and the optimum Ce doping ratio is 5%?n/n?.Finally,photoelectron spectroscopy confirmed that Cr???was reduced to Cr???that were adsorpt on tin disulfide.?2?Photocatalytic degradation of methyl orange by GS/SnS₂ composites.The composites of GS/SnS₂ quantum dots with different proportions were prepared.The XRD,Raman spectra,DRS,TEM,PL spectra and electrochemical properties of the samples were characterized and analyzed.Photocatalytic tests show that GS promotes the photocatalytic degradation of methyl orange on tin disulfide,and the 1%GS/SnS₂ composite has the best photodegradation properties of methyl orange.The results indicate that graphene has good conductivity and favors the separation efficiency of photogenerated carriers.?3?Photocatalytic reduction of CO₂ by tin disulfide materials with different morphologies.A one-step hydrothermal method was used to prepare tablet-like and flower-like SnS₂ photocatalytic material by using different solvents.The BET,XRD,SEM,DRS and other properties of the samples were characterized and analyzed.According to the Mott-Schottky calculation,the potentials of photogenerated electron on the flaky SnS₂ and the flower-like SnS₂ both satisfy potentials for reducing CO₂ to CO or CH₄.The photocatalytic activity of CO₂ on flower-like SnS₂ was higher than that of tablet-like SnS₂.After 4 h of reaction,the photocatalytic efficiency of flowering SnS₂ for CH₄ increased gradually.This indicates that the efficiency and selectivity of photocatalytic reduction of CO₂ by SnS₂ is related to the surface properties.The larger the specific surface area is,the more the number of active sites are,the more favorable the reaction efficiency is,the more abundant the multi-electron aggregation is,and the reaction toward the multi-electron product is more likely to take place.