Microstructure Control And Performance Study Of High Activity Photocatalyst

The article belongs to the research of semiconductor nanomaterials in the field of photocatalysis.The main research object is zinc oxide（ZnO）.The research field includes the application of photocatalysis technology in environmental and energy fields,mainly to control environmental pollution and photolysis of water to produce hydrogen.Increasing the activity and stability of the catalyst and its utilization of visible light are our long-standing goals.Element doping,metal loading,crystal plane control,and preparation of nanocomposite structures are widely used to modify catalysts.In the first chapter,the research background and development of photocatalysis are described,and the development history of photocatalyst is summarized.The preparation methods,development history and photocatalytic mechanism of ZnO and ZnO nanocomposites were comprehensively described.In the second chapter,the ZnO hollow spheres with surface exposed（0001）planes which composed of nano-needle were prepared by one-step hydrothermal method using acetic acid as corrosion agent.ZnO hollow spheres having different（0001）surface exposure ratios can be prepared by varying the solvothermal reaction time.The corrosion degree of acetic acid on the catalyst increases as the reaction time increases.The results of photocatalytic degradation experiments show that the exposure rate of（0001）planes and large specific surface area are both beneficial to photocatalysis.In the third chapter,in order to reduce the band width of ZnO and increase its absorption under visible light,we prepared N-ZnO with urea as nitrogen source,and then prepared N-ZnO/g-C₃N₄ nanocomposites by ultrasonic calcination.The photocatalytic mechanism of N-ZnO/g-C₃N₄ composites was studied and a Z-schesm reaction mechanism was proposed.In the fourth chapter,ZnO was prepared by simple hydrothermal method,and then the prepared ZnO was reacted with a certain amount of thiourea to obtain ZnO/ZnS heterojunction.The prepared ZnO/ZnS catalyst showed good stability in photolysis of water.In the fifth chapter,the ZnO-NiO heterojunction was first prepared,and then it was combined with g-C₃N₄.The degradation rate of ZnO-NiO/g-C₃N₄ was significantly higher than that of g-C₃N₄ and ZnO-NiO heterojunction.It was due to a decrease in the recombination rate of electron holes.The sixth chapter summarizes the experimental work in the previous three chapters and puts forward the innovations and shortcomings of the work.The effective separation of electrons and holes was achieved by the non-metallic element doping of ZnO,the preparation of heterojunction and nanocomposites,and the photocatalytic mechanism was studied.