Preparation And Photocatalytic Properties Of ZnFe₂O₄-based Heterojunctions

In recent years,semiconductor-based photocatalysts have attracted much attention,because of high-efficiency degradation of organic dyes under light.The construction of a heterojunction can effectively improve the performance of photocatalysts,but their wide applications were often restricted by the complex preparation process or the difficulty of recycling（causing the risk of secondary pollution）.Therefore,a convenient and more green method was developed to prepare the magnetic popcorn-like ZnFe₂O₄（ZFO）nanoparticles,and two composite materials ZFO/CdS NPs and ZFO/CdS-GO were prepared by compounding CdS nanoparticles and graphene oxide（GO）materials.The morphological structure and photocatalytic properties of the composite materials were systematically studied,and the following conclusions were obtained.（1）Using zinc acetate as the zinc source and ferric chloride as the iron source,popcorn-like ZFO nanospheres with a uniform size of～300 nm is prepared by a one-step solvothermal synthesis method.（2）Using popcorn-like ZFO nanospheres as the substrate,cadmium sulfide nanoparticles（CdS NPs）were compounded on the surface of popcorn-like ZnFe₂O₄by improved successive ion layer adsorption and reaction（SILAR）,in which the ZFO/CdS NPs heterojunction photocatalyst was obtained.The effect of the loading method of CdS and the number of SILAR cycles on the catalytic performance were studied.The research results show that the FS4-ZnFe₂O₄/CdS sample obtained after 4SILAR cycles has the best photocatalytic degradation performance,after 60 minutes of exposure to visible light,the degradation efficiency of nanocomposites to 10 mg/L Rh B dye reached to 56.44%,and the average degradation rate reached 16.40×10^-3min^-1.（3）In order to further enhance the photocatalytic performance of the ZFO/CdS system,hydrothermal method was proposed to load the prepared GO into the ZFO/CdS precursor,and the ZFO/CdS-GO composite photocatalyst was successfully prepared.The results of the study show that under better experimental conditions,the efficiency of the ZFO/CdS-GO composite photocatalyst to 10 mg/L Rh B solution can reach to 82.68%after 60 minutes of visible light irradiation,and the degradation rate is 31.97×10^-3 min^-1.The introduction of GO reduces the forbidden band width of the system,improve its ability to absorb spectrum and carrier separation efficiency,also increases the specific surface area of the catalyst,which provides more active sites for the photocatalytic degradation process.Therefore,the ZFO/CdS-GO catalytic exhibits more excellent photocatalytic performance.