Preparation And Photocatalytic Performance Of Bi₄Ti₃O₁₂ Based Visible Light Catalyst

As an important technology for solving environmental pollution and energy shortage problems,photocatalytic technology has been attracting more and more attentions.The traditional photocatalyst,TiO2,has been put into practical production and life.However,TiO2 has a wide band gap and low photocatalytic efficiency,which limits its further development.Therefore,the search for new high-efficienct photocatalysts and modified traditional photocatalysts has become a research hotspot in the field of photocatalysis.In this thesis,we studied the synthesis,photocatalytic performance and photocatalytic mechanism of Bi4Ti3O12-nLaFeO3(n=0.5,1,1.5),Bi4Ti3O12-yBiCoO3(m=0.5,1)and piezo-photocatalyst Na0.5Bi0.5TiO3.Nanosheet-assembled flower-like semiconductor photocatalysts Bi4Ti3O12-nLaFeO3(n=0.5,1,1.5)with a large specific surface area,strong light absorption ability and excellent photocatalytic effect were synthesized by hydrothermal process.And the photocatalytic properties of the Bi4Ti3O12-nLaFeO3(n=0.5,1,1.5)material was tested.The result show that with the increase of LaFeO3 content in the Bi4Ti3O12-nLaFeO3(n=0.5,1,1.5)photocatalysts,the optical absorption and photocatalysis ability of the material show regular enhancement.Among the three materials,Bi4Ti3O12-1.5LaFeO3 photocatalyst has the best photocatalytic activity,which can reduce the concentration of RhB in acid environment(HCl,pH=2)by 98%in 50 min.And the Bi4Ti3O12-nLaFeO3(n=0.5,1,1.5)also has a good cycle stability,which can carry out photocatalytic reaction with high efficiency for a long time.Moreover,we found that Bi4Ti3O12-nLaFeO3(n=0.5,1,1.5)photocatalysts were decomposed into BiOCl nanosheets under HCl condition,and the obtained Bi4Ti3O12-nLaFeO3(n=0.5,1,1.5)&BiOCl heterojunctions exhibited excellent photocatalytic activities under neutral condition.This may be one of the reasons why the Bi4Ti3O12-nLaFeO3(n=0.5,1,1.5)photocatalysts just have good photocatalytic activities with HC1.Based on the above experiments,a fundamental mechanism for the degradation of RhB in acid environment by Bi4Ti3O12-nLaFeO3(n=0.5,1,1.5)was proposed.Nanosheet like Bi4Ti3O12-mBiCoO3(m=0.5,1)semiconductor photocatalysts with strong light absorption ability and excellent photocatalytic effect were synthesized by hydrothermal process.The Bi4Ti3O12-BiCoO3 sample also has a strong adsorption ability to RhB and MO with efficiencies of 55.15%,68.33%in 30 min.And,the Bi4Ti3Oi2-BiCoO3 sample exhibits visible light-driven photocatalytic degradation of RhB,MO,Dye Red and Dye Blue in acid environment(HCl,pH=2).At the same time,Bi4Ti3Ol2-mBiCoO3(m=0.5,1)also has good cycle stability and can carry out photocatalytic reaction with high efficiency for a long time.The trapping experiment results show that the main action ions are h+ and ·O2-in the process of degradation of organic dye RhB by semiconductor photocatalyst Bi4Ti3O12-mBiCoO3.Based on the results of trapping experiment,the possible working mechanism of the RhB degradation with semiconductor photocatalyst Bi4Ti3O12-mBiCoO3 in acidic aqueous solution has been proposedMicrometer cuboid like Na0.5Bi0.5TiO3 piezo-photocatalyst was synthesized by hydrothermal method.RhB can be rapidly degraded by piezoelectric semiconductor Na0.5Bi0.5TiO3 under the irradiation of ultrasound and visible light.and the degradation efficiency is 4 times of that only under ultrasonic vibration.The trapping experiment results show that the main action ions are ·OH and ·O2-in the process of degradation of organic dye RhB by piezo-photocatalyst Na0.5Bi0.5TiO3.Combined with the photocatalysis experiment and the stability experiment,we reasonably speculated on the reaction mechanism of the piezo-photocatalyst Na0.5Bi0.5TiO3 degradation of organic dye RhB.