Photoelectrical And Electrochemical Properties Of Tungsten Oxide Heterojunction Composites

Solar energy is a green energy of nature.As long as people make reasonable utilization of it,we can effectively solve the energy problem and environmental pollution problem that people are facing today.Among them,as a high-tech and efficient conversion technology,photoelectrocatalysis can convert solar energy into chemical energy and solve the energy shortage on the earth,and improve the environmental pollution.In the field of photoelectrocatalysis,semiconductor materials are used as photocatalysts.As a common photocatalyst,tungsten trioxide?WO₃?has been widely utilized in solar energy conversion and environmental pollution purification.However,the electronic reduction ability of WO₃ is very poor,which seriously affects its photoelectrocatalytic activity.Therefore,in this paper,we have synthesized different heterojunction composite materials based on tungsten oxide,in order to improve their photoelectrochemical properties.The main research contents are as follows:1.WO₃/Sb₂S₃ heterojunction materials with the different deposition time are prepared by chemical deposition.The structure,morphology and element composition of the heterojunction are analysed,and its photoelectrochemical properties are studied by common photoelectrochemical test methods.The experimental datas show that the photocurrents of WO₃/Sb₂S₃ heterojunction materials are much higher than that of WO₃ itself under visible light irradiation,and the performance of WO₃/Sb₂S₃?4h?is 6 times higher than that of WO₃.In addition,we also study the application of WO₃ and WO₃/Sb₂S₃ heterojunction materials in the photoelectrocatalytic reduction of CO₂ system,and finally obtain the reduction product formic acid of CO₂.Through datas calculation,we can see that the formic acid yields of WO₃/Sb₂S₃ heterojunction materials are generally higher than that of WO₃ itself,and the yield of WO₃/Sb₂S₃?4h?reaches 413 nmol/cm².These datas further prove that the WO₃/Sb₂S₃heterojunction materials can improve the photoelectrochemical properties of WO₃.2.WO₃/BiOI heterojunction materials with different precursor concentrations are synthesized by hydrothermal growth of the BiOI nanoplates.The crystal structure and element composition of the heterojunction materials are analysed.We also have studied the photoelectrochemical properties by using the photoelectrochemical characterization method.The test datas show that the WO₃/BiOI heterojunction materials own stronger light absorption capacity under the visible light irradiation,and the photocurrent value of WO₃/BiOI?0.4mmol?is 5.3 times higher than that of WO₃ itself.In addition,we study the photoelectrocatalysis of reducing CO₂.Through the experiment,we get another reduction product methanol of CO₂.The yield of WO₃/BiOI?0.4 mmol?reaches to 373 nmol/cm²,and WO₃ couldn't produce the methanol,WO₃/BiOI heterojunction materials possess stronger photoelectrochemical properties and carbon dioxide reduction properties.