Preparation Of Morphology-controlled Photocatalysts And Their Photocatalytic Performance Of CO₂ Reduction

High concentration of CO₂ in atmosphere from coal burning has caused various environmental problems and attracted great attention of global scholars.The chemical conversion of CO₂ is a green and sustainable energy path.Photocatalytic reduction of CO₂has unique advantages such as no secondary pollution,using solar resources,easy to operation and so on.In this thesis,the photocatalytic CO₂ reduction performance of the prepared catalysts by the yield of methyl formate?MF?in methanol was studied.The main research contents are as follows.?1?Anatase and B dual-phase TiO₂ microspheres were prepared by a mild sovlothermal method,then copper oxide was doped into the dual-phase TiO₂ by immersion process.The results indicate that the prepared sample is TiO₂?A?and TiO₂?B?mixed-phase microsphere structure,which has superior morphology regularity and particle dispersion than TiO₂?A?.The miscible structure and CuO doping significantly improve the absorption ability of ultraviolet and visible light,reducing the recombination rate of electron holes and prolong the electron lifetime,which contributes to the highest MF fornartion rate up to 452.2?mol·g^-1·h^-1.CuO/TiO₂?AB?also shows good reusability and stability during the photocatalytic reaction process.?2?Metal organic framework?MOFs?is a kind of porous crystaline materials.It has the characteristics of controllable morphology and flexible adjustment of functional groups.Here the study of morphology-controlled photocatalysts was based on MIL-125?Ti?.It was modified by introduction of–NH₂ group to the ligand and constructing composite with reduced graphite oxide?rGO?.When introduced with rGO,the dispersion of MOF particles is better.Amino and rGO doping significantly improve the pure MIL-125ultraviolet and visible light absorption ability,and reduce the photoproduction electron-hole recombination rate.rGO as a good electrical conduction could prolong the life of electronic.rGO@NH₂-MIL-125 shows high MF production under light up to 1116.2?mol·g^-1·h^-1.It also exhibits good stability in repeatability experiments.?3?Multiple metal sulfide ZnIn₂S₄ has diverse morphology structure.It is a kind of semiconductor material well known for its excellent photocatalytic performance.Based on this,the photocatalyst ZnIn₂S₄ for morphology controlled was studied.Four kinds of ZnIn₂S₄ with different size and morphology were prepared by controlling solvent,sulfur souce,pH and heat preservation conditions.The results show that flower-like ZnIn₂S₄,flower-like shell ZnIn₂S₄,ZnIn₂S₄ nanoflower and ZnIn₂S₄ microsphere are all of the hexagonal crystalline forms.They have abundant mesoporous structure and their specific surface areas both higher than 100 m²/g,expect for ZnIn₂S₄ nanoflower.The absorptivity of ultraviolet and visible light is different due to the different morphology.The highest MF production rate is up to 1139.0?mol·g^-1·h^-1 when ZnIn₂S₄ microspheres are used as the catalysts.Four kinds of ZnIn₂S₄ materials also show good stability in repeatability experiments.