Preparation Of TiO₂-based Compound Semiconductor And Study On Its Photocatalytic Performance

The current global warming caused by climate change is one of the environmental change crises facing mankind.In addition,the carbon dioxide（CO₂）produced by the burning of traditional fossil fuels will further aggravate the trend of global warming.For a long time,researchers have been trying to find effective solutions to reduce CO₂emissions.Among them,electrochemistry or hydrogenation to convert it into hydrocarbon fuel was once considered to be one of the most promising methods.However,these processes require extremely high operating costs and are accompanied by a huge consumption of energy.In recent years,under the irradiation of simulated sunlight,photocatalytic reduction of CO₂into hydrocarbon fuel,that is,conversion of CO₂to CH₄,has become the most economical and green solution at present.The traditional photocatalytic system for this reaction is titanium dioxide（TiO₂）,which has many advantages,such as light stability,extremely high catalytic activity,low toxicity and low cost.However,TiO₂is a wide band gap（3.2e V）semiconductor material,which mainly absorbs ultraviolet light,while the utilization efficiency of visible light is relatively low.In addition,TiO₂has a relatively short photogenerated carrier lifetime,and relatively low mobility of photogenerated electrons and holes,which limits its application in practical industrialization.Therefore,in this paper,we made some modifications to TiO₂and studied its photocatalytic performance.The main research content and results of the thesis are as follows:（1）The CeO₂/TiO₂composite material was prepared by the sol-gel method.At the same time,a series of CeO₂/TiO₂samples with different ratios were synthesized.Using XRD,PL,SEM and other methods to explore and analyze the samples.Taking the photocatalytic reduction of CO₂as the criterion,the reduction activity of CeO₂/TiO₂under a 300W xenon lamp light source was explored.When the ratio of CeO₂/TiO₂is1:7,the output of CH4 is about 3 times higher than that of pure TiO₂.（2）Using tetrabutyl titanate as the titanium source,pure TiO₂powder（anatase type）was prepared by hydrothermal solvent method,and then Cu Fe₂O₄and TiO₂were compounded to prepare Cu Fe₂O₄/TiO₂composite material.Cu Fe₂O₄/TiO₂was used in the photocatalytic reduction of CO₂test.The test results show that under the action of simulated sunlight,the composite material exhibits excellent photocatalytic reduction of CO₂activity.When 15%Cu Fe₂O₄/TiO₂is used as the photocatalyst,the rate of CH₄generation is the highest,which is about 2 times higher than that of pure TiO₂.In addition,PL,XRD,SEM,UV-Vis and other analytical methods were used to explore the samples,which proved the smooth synthesis of Cu Fe₂O₄/TiO₂.（3）Using isopropyl titanate as the titanium source,Cu/TiO₂composite materials with different ratios were successfully prepared and applied to the experiment of photocatalytic reduction of CO₂.The experimental results show that under the action of simulated sunlight,the composite material exhibits excellent photocatalytic reduction activity of CO₂.When 1.5 Cu/TiO₂is used as a photocatalyst,the CH₄generation rate is the highest,which is more than 2 times higher than that of pure TiO₂.In addition,UV-Vis spectroscopy,XRD,EIS,etc.were used to analyze and study the materials,and the reaction mechanism of photocatalytic reduction of carbon dioxide by composite materials was discussed.