Band Gap Regulation,Modification And Properties Of Photocatalytic Material ZnS

With the widespread use of organic substances,such as pesticides,dyes,drugs and cosmetics,a large number of aromatic compounds have been produced.These aromatic compounds pose a great threat to human health and ecosystem balance through the accumulation of food chains.Traditional photocatalysts,such as TiO₂,have attracted much attention because of its low cost,innocuity and simplicity in preparation.However,the application of TiO₂ is limited because it only responds to ultraviolet light.Therefore,it is very important to find a visible light-driven semiconductor photocatalyst to degrade aromatic compounds in the environment.Visible light accounts for 46%of the total solar energy.In order to make full use of solar energy and improve the photocatalytic activity of photocatalysts,many research efforts have been made to explore non-toxic,recyclable and excellent photocatalysts.ZnS is an n-type semiconductor material.Because of its rich morphology,excellent physical properties and unique photocatalytic properties,it has attracted extensive attention,but also because of its wide band gap,the utilization efficiency of visible light is limited.In this paper,band gap engineering is used to control the composition or crystal structure of semiconductors or composites to change the band gap of ZnS,so as to promote its optical absorption efficiency and improve its visible light photocatalytic activity.The specific contents of the study are as follows:（1）One-step solvothermal method was used to prepare band gap controllable ZnS-MoS₂ solid solution visible light catalyst by adjusting the molar ratio of Zn/Mo.In the experimental system,different molar ratio of Zn/Mo,the band gap,specific surface area,photocatalytic activity and morphology of ZnS-MoS₂ solid solution were different.When Zn:Mo was 30:1,the visible light photocatalytic performance of the synthesized ZnS-MoS₂ solid solution was the best,which showed good stability after four cycles of experiments.（2）In order to improve the visible light photocatalytic efficiency of ZnS-MoS₂solid solution,graphene was introduced into the synthesis process,and the rGO/ZnS-MoS₂ composite was prepared by one-step solvothermal method.The degradation of 2-nitrophenol with the prepared material shows that the catalytic performance of the 11%rGO/ZnS-MoS₂ composite was the best.Under the visible light radiation,the degradation efficiency of 2-NP was 90.57%,and the COD removal efficiency of practical pharmaceutical wastewater was 74.05%.（3）One step hydrothermal method is adopted to prepare Zn_1-xIn_2x/3S solid solution visible light driven photocatalyst with adjustable band gap by controlling the Zn/In molar ratio.After optimizing the atomic ratio of Zn/In,the photocatalytic activity of Zn_0.6In_0.27S solid solution is the best,and it has good degradation effect on aromatic compounds.Under visible light irradiation,the degradation efficiencies of Zn_0.6In_0.27S solid solution for 2-nitrophenol,chloramphenicol,4-nitrophenol and ceftriaxone sodium were 97.10%,89.76%,96.01%and 87.02%,respectively.The contents of NO₃^-in the final degradation solution of chloramphenicol,ceftriaxone sodium,2-NP and 4-NP were 0.619,0.667,2.912 and 1.703 mg/L,respectively,and 2.005 mg/L Cl^-was also detected in the final degradation solution of chloramphenicol.Besides,the degradation paths of this four pollutants were also analyzed and predicted by LC-MS.In addition,The toxicity experiment in E.coli showed that the solid solution of Zn_1-x-x In_2x/3S had a good antitoxicity to biological toxicity.