Preparation And Photocatalytic Activity Of CeO₂ Composites

Photocatalytic energy can realize the catalytic degradation of organic pollutants in water by using solar energy,with low energy consumption and no secondary pollution.It is one of the most promising technologies in the field of water treatment.Cerium dioxide(CeO2)is simple to prepare,cheap and easy to obtain,but CeO2 can only absorb part of visible light,resulting in low photocatalytic efficiency and can not be widely used in water treatment.Barium titanate and bismuth vanadate have a corresponding wavelength of light of about 500 nm,which is higher than that of CeO2.However,its photogenerated electrons and holes are easily recombined,which reduces the photocatalytic efficiency to some extent.In view of the shortcomings of CeO2,the absorption wavelength range of CeO2 can be broadened by doping the metal elements Bi,Ti and V,the recombination of photogenerated electrons and holes can be reduced,the photocatalytic activity can be improved,and the photocatalytic degradation of water pollutants can be accelerated.The content is as follows:Bismuth titanate/cerium dioxide(Bi4Ti3O12/CeO2)composite photocatalytic material was prepared by hydrothermal synthesis and CeO2 as carrier.Bi4Ti3O12/CeO2 composites were characterized by scanning electron microscopy(SEM),X-ray powder diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR)and UV-visible diffuse reflectance spectroscopy(Uv-vis),.Morphological characterization,crystal phase structure and spectral analysis were performed.The results show that the spherical Bi4Ti3O12 is supported on the bouquet CeO2 to form a composite structure.The photocatalytic activity of Bi4Ti3O12/CeO2 was studied under the irradiation of simulated sunlight with methylene blue as the target degradant.When the molar ratio of Bi4Ti3O12 to CeO2 is 20%,the hydrothermal time is 24 h,the hydrothermal temperature is 180 ?,the initial concentration of methylene blue solution is 30 mg/L and the dosage of Bi4Ti3O12/CeO2 composite is 0.8 g/L.After photocatalytic reaction for 180 min,The decolorization rate of the methylene blue solution was about 81.13%.Bismuth vanadate/bismuth oxide(BiVO4/CeO2)composite photocatalyst was prepared by hydrothermal synthesis using ammonium metavanadate(NH4VO3)as vanadium source.The results of SEM,XRD and FT-IR showed that BiVO4 particles were supported on the CeO2 bouquet to form a composite structure.The effects of the molar ratio of composites,hydrothermal temperature,hydrothermal time,initial concentration of methylene blue solution,solution p H and dosage on the photocatalytic ability of BiVO4/CeO2 composites were investigated under simulated sunlight.The results show that the prepared BiVO4/CeO2 photocatalyst has good photocatalytic activity for methylene blue compared with pure phase granular BiVO4 and bouquet-like CeO2.When the molar ratio of BiVO4 to CeO2 is 20%,the p H of the methylene blue solution is 8,the hydrothermal temperature is 90 ?,the hydrothermal time is 24 h,and the dosage of BiVO4/CeO2 is 1.0 g/L,the photocatalytic activity of the composite is over 91%.