Study On Design And Application Of Vanadate Composite Photocatalyst

Among many highly efficient semiconductor photocatalysts,rare earth orthovanadates have attracted widespread attention in various fields due to their potential applications in recent technologies and alternative green technologies.Although BiVO₄has a good absorption range for light in the visible light region,its practical applications in the fields of photocatalytic degradation of organic pollutants and water cracking are hindered by the poor separation efficiency of electrons and holes,and the low conductivity of BiVO₄.Based on the above issues,three kinds of BiVO₄ based composite materials were prepared and photocatalytic studies were conducted on the prepared samples.The specific research content is as follows:（1）The Z-type Ag/g-C₃N₄/BiVO₄visible-driven bifocal photocatalyst promoted by Ag isionogen was synthesized by high temperature solid phase method,hydrothermal reaction and photoreduction surface deposition method,and the dye degradation and bacteriostatic were carried out.The Ag/g-C₃N₄/BiVO₄ terpolymer with Ag nanoparticles showed the best photocatalytic activity,and the degradation efficiency of organic pollutants Rh B reached 95%in 80 min,and it also had a good antibacterial effect on Escherichia coli.On the one hand,the increase of Ag/g-C₃N₄/BiVO₄ can be attributed to the formation of Z-type heterojunction structure,which inhibits the photogenerated electron-hole pair recombination and improves the photocatalytic efficiency.On the other hand,the isoplasmon resonance effect caused by Ag nanoparticles broadens the absorption range of visible light.Therefore,Ag isoplasms promoting Z-type Ag/g-C₃N₄/BiVO₄ ternary composites can improve the separation of photoinduced carriers,which can be used for large-scale practical applications such as wastewater treatment and pollution control.（2）Bi/BiVO₄binary composites modified with non-noble metal Bi quantum dots were prepared by semi-solvothermal method with H₂O and DMF as solvents under mild conditions.DMF not only acts as a solvent to inhibit the hydrolysis of Bi(NO₃3)·5H₂O,but also acts as a reducing agent to generate metal Bi.The Bi/BiVO₄-25 photocatalyst prepared by adding 25m L DMF showed the best photocatalytic activity,and the degradation efficiency of organic pollutant MB reached 90%within 70 min.The photocatalytic improvement of Bi/BiVO₄-25samples was mainly attributed to the introduction of Bi quantum dots.On the one hand,the plasmon resonance effect caused by Bi quantum dots widens the absorption range of visible light and reduces the optical reflectance to obtain more solar energy.On the other hand,after Bi quantum dots deposition,the band gap of the composite becomes narrower,which enhances the transition of electrons from valence to conduction band of the prepared nanocomposites,and these electrons participate in the subsequent photocatalytic process.（3）Bi/BiVO₄/WO₃terpolymer with different content of WO₃ was prepared by hydrothermal reaction using Bi/BiVO₄-25 as matrix,and its photocatalytic performance was studied.The Bi/BiVO₄/WO₃-12%terpolymer loaded with 12 wt%WO₃ has the best photocatalytic degradation effect on MB under visible light.The improvement of photocatalytic activity is mainly attributed to the formation of Z-type heterojunction structure,which reduces the photoelectron-hole pair recombination and improves the photocatalytic efficiency.