Study On The Preparetion And Performance Of SnS₂/ZnO

Semiconductor photocatalysis provides a green and efficient technology for environmental governance,which has applied in pollution management of air,water and soil.SnS₂ is a narrow band gap?2.2eV?semiconductor with strong ability to absorb visible light.But its photocatalytic activity is low due to the easily recombination of photogenerated electron and hole.ZnO is a wide band gap?3.2eV?semiconductor with possessing high electron mobility and faster photoproduction electronic transmission.It is one of the excellent photocatalysts,but it can only absorb ultraviolet light because of its wider band gap.They are widely used because of their stable physical and chemical properties and low cost,but there are some shortcoming when using a single material as a photocatalyst or gas sensing material.So compositing two semiconductor to give full play to their strengths for improving its photocatalytic properties and gas sensing performance is a significant subject.In this paper,SnS₂ with different morphologies were synthesized by using hydrothermal method or solvothermal method with tin chloride and thioacetamide as raw materials.Then the SnS₂/ZnO heterojunctions were geted after dopeding different amounts ZnO using precipitation method.The structure,composition,morphology and optical properties of the prepared samples were characterized by XRD,FESEM,SEM,UV-Vis and PL.The photocatalytic performance and gas sensing performance of samples were also tested.The main research contents and results are as followes:1.SnS₂ particles were synthesized by using hydrothermal method with tin chloride,thioacetamide and citric acid as raw materials.Then the SnS₂/ZnO heterojunctions were geted after dopeding different amounts ZnO using precipitation method.Then the photocatalytic performance and gas sensing performance of samples were tested.The results indicated that 1 wt% ZnO-doped SnS₂ showed the best photocatalytic activity,which can reach degradation rate of 100% to 20mg/L K₂Cr₂O₇ under 80 min visible light irradiation.The degradation rate of SZ-1 increased by 24% than that of pure SnS₂?76%?,and 86% than that of pure ZnO?14%?.Moreover,SZ-1 gas sensor showed the best gas sensing performance to NO₂.SZ-1 gas sensor possessed superior sensitivity?466?to 10 ppm NO₂,which is 2.7 times of pure SnS₂?172?and 212 times of pure ZnO?2.2?.SZ-1 can detect NO₂ in a wide concentration range,which possessed superior sensitivity?12.3?to 1ppm NO₂.The response time is only 7s and the recovery time is only 49 s.Also,SZ-1 showed a superior selectivity to NO₂ and long-term stability.It is likely to be related to the band gap,fluorescence and heterojunction structure.2.The flower-like SnS₂ were synthesized by using solvothermal method with tin chloride,thioacetamide and ethanol as raw materials.Then the SnS₂/ZnO heterojunctions were geted after dopeding different amounts ZnO using precipitation method.Then the photocatalytic performance and gas sensing performance of samples were tested.The results indicated that 1wt% ZnO-doped Sn S2 showed the best photocatalytic activity,which can reach degradation rate of 45% to 20mg/L K₂Cr₂O₇ under 120 min visible light irradiation.The degradation rate of SZ-1 increased by 15% than that of pure SnS₂?30%?,and 28% than that of pure ZnO?17%?.Moreover,SZ-1 gas sensor showed the best gas sensing performance to NO₂.SZ-1 gas sensor possessed superior sensitivity?363.5?to 10 ppm NO₂,which is 4.5 times of pure SnS₂?81.2?and 165 times of pure ZnO?2.2?.SZ-1 can detect NO₂ in a wide concentration range,which possessed superior sensitivity?51.5?to 5ppm NO₂.The response time is only 3s and the recovery time is only 49 s.Also,SZ-1 showed a superior selectivity to NO₂ and long-term stability.It is likely to be related to the band gap,fluorescence and heterojunction structure.3.Pine needle-like ZnO with superior visible light photocatalytic activity and gas sensing performance were successfully synthesized via sol-gel and calcinations method using Zinc nitrate,citric acid and cotton fiber as raw materials.The effect of preparation conditions on the ZnO morphology and photocatalytic performance were investigated,including calcination temperature and heating rate.The result showed that ZnO-3 which is synthesized at 500?C calcination temperature and 3?C/min heating rate is uniform pine needles-like.Moreover,ZnO-3 showed better photocatalytic activity than other ZnO samples,which can reach degradation rate of 97.7% to 10mg/L Reactive Black solution under 60 min visible light irradiation.ZnO-5 which is synthesized at 500?C calcination temperature and 5?C/min heating rate showed excellent gas sensing performance.ZnO-5 gas sensor possessed superior sensitivity?516?to 100 ppm ethanol at optimum working temperature 350?C.Zn O-5 can detect ethanol in a wide concentration range,which possessed superior sensitivity?12?to 5ppm ethanol.The response time is only 15 s and the recovery time is only 7s.Also,ZnO-5 showed a superior selectivity to ethanol and long-term stability.It is likely to be related to the particle size,the degree of crystallization,the band gap and fluorescence.