| BiOI?Bismuth iodide?,as a new type of photocatalytic semiconductor,has attracted interest due to its excellent photocatalytic activity and excellent structural properties.BiOI has the smallest band gap among bismuth halide materials,which has the most extensive absorption range and the best photocatalytic activity.The open layered structure can make the atom and orbit fully polarize and promote the electric charge movement.However,the photogenerated electrons and holes could recombine easily because of the narrow band gap,so BiOI still has some limitations.In this study,in order to improve the photocatalytic performance of BiOI,ZnWO4?Zinc tungstate?,SnO2?Tin oxide?,CeO2?Cerium oxide?and MgO?Magnesium oxide?were selected to modify BiOI,respectively.Degradation of methylene blue was used to analyze its photocatalytic performance under visible light.The main contents are as following:1.Preparation and photocatalystic properties of ZnWO4/BiOI composites:ZnWO4 was obtained by the hydrothermal process with Zn?Ac?2·2H2O and Na2WO4·2H2O as the raw materials.ZnWO4/BiOI composite photocatalysts were synthesized via a facile water bath method.The as-prepared samples were characterized by X-ray powder diffraction?XRD?,scanning electron microscopy?SEM?,transmission electron microscopy?TEM?,UV-Vis diffusion reflectance spectroscopy?DRS?and photoluminescence?PL?spectroscopy,respectively.The photocatalytic activity of ZnWO4/BiOI photocatalyst was investigated via degradation of methyl blue dye?MB?under the visible-light.The results showed that the ZnWO4:BiOI with molar ratio of 5:5?ZB-5?displayed the highest photocatalytic activity.After4 hours of visible light irradiation,the degradation efficiency of ZB-5 to MB dye was close to 100%.The promotion of the photocatalytic activity was primarily resulted from the effective separation of photogenerated electron-hole pairs.According to the radical scavengers experiments,·O2-and h+play the important roles during the degradation process.2.Preparation and photocatalystic properties of Sn O2/BiOI composites:Sn O2/BiOI composite photocatalysts were prepared by a thermostatic heating.The as-prepared samples were characterized by XRD,SEM,TEM,DRS and PL,respectively.The photocatalytic activity of Sn O2/BiOI photocatalyst was investigated by degradation of methyl blue dye?MB?under visible light irradiation.The results implied that Sn O2:BiOI with the molar ratio of 7:3?SB-7?showed the highest photocatalytic activity.The enhancement of the photocatalytic property was mainly due to the effective separation of photogenerated electron-hole pairs.According to the radical scavengers experiments,·OH and h+play the important roles during the degradation process.3.Preparation and photocatalystic properties of CeO2/BiOI composites:CeO2was obtained by the calcination method with Ce?NO3?3.6H2O as the raw material.CeO2/BiOI composite photocatalysts were prepared by a hydrothermal process using ethylene diamine tetraacetic acid?EDTA?as chelating agent.The as-prepared samples were characterized by XRD,SEM,TEM,DRS and PL,respectively.The photocatalytic activity of CeO2/BiOI photocatalyst was investigated by degradation of methyl blue dye?MB?under visible light irradiation.The results implied that CeO2:BiOI with the molar ratio of 3:7?CB-3?showed the highest photocatalytic activity and the degradation rate of MB reached nearly 100%after photoreaction for90 min.And experiments and Analysis on the reutilization and stability of CB-3were carried out.4.Preparation and photocatalystic properties of MgO/BiOI composites:MgO was obtained by the calcination method with Mg?NO3?2.6H2O as the raw material.Mg O/BiOI composite photocatalysts were prepared by a facile water bath method.The as-prepared samples were characterized by XRD,SEM,TEM,DRS and PL,respectively.The photocatalytic activity of Mg O/BiOI photocatalyst was investigated by degradation of methyl blue dye?MB?under visible light irradiation.The results implied that Mg O:Bi OI with the molar ratio of 5:5?MB-5?showed the highest photocatalytic activity.According to the radical scavengers experiments,·OH and h+play the important roles during the degradation process. |
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