Study On The Preparation,Modification,and Photocatalvtic Activity Of Titanium Dioxide Photocatalyst

In last decades,the problem in water pollution has attracted more and more attention,the organic-rich water influences the microorganism lives and then breaks the ecological balance.How to solve the problem in water pollution has become a focus of society.Titanium dioxide(TiO2),one of the most significant oxide catalysts,has been widely applied in the fields of environment and energy.Among all of the TiO2 polymorphs,the anatase TiO2 has attracted the most researchers due to its excellent properties in catalytic field.But with the further development of TiO2research,the photo degradation efficiency of TiO2 photocatalystshas limited due to its high-recombination of photoelectron-holepairs and wide band gap,which would bring the problem for low utilization efficiency and low quantum efficiency.Low-cost synthesis of TiO2 catalysts with excellent photocatalytic activity stills a giant challenge for researchers.This study focused on controlled synthesis of TiO2 photocatalyst with different microstructure by solvothermal method,and structure,modifying and properties are also illuminated.The researches results can be concluded to the following four areas:(1)Three-dimensional spherical anatase TiO2 photocatalysts were prepared by a solvothermal method at different temperature.X-ray diffraction(XRD)exposed that the products have the pure anatase structure.Scanning electron microscope(SEM)indicated that the morphology of TiO2 samples are spherical microstructures,and can be controlled by changing the solvothermal reaction temperature.The band gap of TiO2 photocatalysts fabricated at 150 ?,175 ? and 200 ? is 3.16 eV,3.09 eV and 3.11 eV,respectively.The photocatalytic properties of as-prepared TiO2 photocatalysts were analyzed by the photodegradation of rhodamine B water solutions under UV light irradiation at normal temperature.TiO2 photocatalysts show excellent property for the photodegradation of rhodamine B,which is better than that of the commercial P25.According to the experimental effects,the photocatalytic properties of TiO2 photocatalysts depend largely on the band gap,crystallinity and crystalline size of crystal.(2)3D tubular hierarchical TiO2 microstructurewere successfully obtained by a solvothermal method at 110 ? for 24 h.X-ray diffraction(XRD)exposed that the products have the pure anatase structure.The images of Scanning electron microscope(SEM)and transmission electron microscope(TEM)indicated that the morphology of TiO2 samples is 3D tubular hierarchical TiO2 microstructure.The band gap of3D tubular hierarchical TiO2 microstructure is 3.22 eV,which is higher than that of monolithic TiO2(3.2 eV).And the specific surface area of TiO2 samples is 136.74m2/g.The photocatalytic properties of as-prepared TiO2 photocatalysts were analyzed by the photodegradation of rhodamine B water solutions under UV light irradiation at normal temperature.The rate constant of 3D tubular hierarchical TiO2 microstructure is 0.018 min-1,which is better than that of the commercial P25(0.013 min-1).(3)TiO2 nanotube and TiO2-ZnO composite photocatalysts were fabricated by simple solvothermal method.From the Tauc plot of prepared samples,the optical energy gap ofZnO,TiO2 nanotube and TiO2-ZnO composite photocatalysts werecomputed to be 3.34 eV,3.22 eV and 3.12 eV,respectively.The photocatalytic property of as-prepared samples was analyzed by the photo degradation of rhodamineB water solutions under visible light irradiation.The rate constant of ZnO,P25,TiO2 naotube and TiO2-ZnO composite photocatalysts are 0.0023 min-1,0.0059 min-1,0.0085 min-1 and 0.011 min-1,respectively.The prepared TiO2-ZnO composite photocatalystsexhibited excellent property in photo degradation of rhodamine B water solution,which is betterthan that of P25.The enhancement photocatalytic property of target photocatalysts could be attributedto the reduced band gap energy,the enhanced-surface physic-chemical properties,the separation ofphoto induced electron-hole pairs and the decreased recombination rate.In addition,TiO2-ZnO compositephotocatalysts showed good stability for rhodamine B photo degradation under visible light irriadation.(4)Ag/TiO2 hollow microstructure was obtained by simple solvothermal method.X-ray diffraction(XRD)exposed that the products have the pure anatase structure.The images of scanning electron microscope(SEM)and transmission electron microscope(TEM)indicated that the morphology of TiO2 samples ishollow microstructure.Metallic silver as the photo-generated electrons temporary,gathering place with a timely transfer of electron-hole pairs,slower electron-hole pair recombination,enhanced carrier utilization and increased Ag/TiO2 hollow microstructure photocatalytic activity.The rate constant under visible irradiation of P25,pure TiO2 and Ag/TiO2 compositephotocatalysts is 0.0041 min-1,0.0088 min-1 and 0.0133 min-1,respectively.Ag/TiO2 hollow microstructure exhibited excellent property in photo degradation of rhodamine B water solution.