Modification And Properties Of ZnO And MIL-101(Fe) Photocatalysts

The urgent need to address environmental pollution in the context of sustainable development has made semiconductor photocatalytic technology a popular research field.ZnO and MIL-101（Fe）have gained attention due to non-toxic,low cost,stable properties,and excellent photoelectric performance.However,their photocatalytic performance needs further improvement as they exhibit a relatively high carrier recombination rate.Therefore,this study focused on the rare earth element doping and heterostructure construction of ZnO and MIL-101（Fe）,and investigated in detail the effects of different rare earth dopants and composite ratios on their composition,morphology,and photocatalytic performance.The specific research contents are as follows:ZnO-based nanophotocatalyst materials doped with different proportions of Tb and different rare earth elements（La,Yb,Nd）were prepared by solvothermal method.Combined with XRD,SEM,FT-IR,Raman,XPS,PL,BET,EIS,UV-vis test methods and evaluation of the degradation effect on simulated pollutants.The results show that rare earth doping ZnO does not change its crystal structure,and rare earth ions entering the ZnO lattice will replace Zn²⁺to adjust the electronic structure of the original ZnO,and at the same time play the role of refining the grain,effectively hinder the recombination of electron-hole pairs,improve the utilization efficiency of ZnO for solar energy,and reduce the band gap of the catalyst.When doped with 3%Tb,it has the greatest effect on ZnO photocatalyst and its degradation performance is the best.Graphene dispersions were prepared by the Hummers’method with a redox process,followed by the synthesis of ZnO,3Tb-ZnO,and 3Tb-ZnO/RGO photocatalysts using a solvothermal method.Combined with various of characterization methods and the evaluation of the degradation effect on simulated pollutants,the structure,morphology and optical properties of photocatalysts were studied.Due to the introduction of Tb³⁺,the impurity energy level is formed,which reduces the recombination of photogenerated electron-hole pairs,changes the band structure of pure ZnO,broadens its light absorption range.Moreover,the incorporation of RGO has a significant impact on the optical properties of both ZnO and 3Tb-ZnO,leading to a reduced band gap,thus expanding the range of light response.Among them,3Tb-ZnO/12RGO exhibits the best photocatalytic performance,with a reaction rate constant as high as 0.04 min^-1.MIL-101（Fe）/3Tb-ZnO composites were prepared by solvothermal method and characterized by various test methods.It was found that after MIL-101（Fe）was combined with3Tb-ZnO,the defect sites and oxygen vacancies on the surface of the material increased,the band gap value decreased significantly,and the separation and transfer of electron-hole pairs were accelerated.The results of photocatalytic degradation show that compounding an appropriate amount of 3Tb-ZnO can greatly improve the photocatalytic performance of MIL-101（Fe）material,and 4ZT-M has the highest photocatalytic degradation efficiency,and the degradation rate of Rh B reaches 100%in 60 min,which is 4.5 times that of pure MIL-101（Fe）.At the same time,the effects of different factors（initial concentration of pollutants,amount of photocatalyst,p H）and different pollutants on the photocatalytic performance were studied.Finally,the photocatalytic mechanism of the composite was analyzed by combining the free radical capture experiment and the determination of the energy band position.