Preparation And Photocatalytic Properties Of Based Bi₂O₃ Composite Photocatalyst

Photocatalytic technology has the characteristics of zero pollution,low cost and thorough sustainability.It has become an ideal way to solve the fossil energy crisis and control environmental pollution.The core of the photocatalyst is the photocatalyst.The wide band gap material TiO2 and g-C3N4 have suitable band structure and good stability,and are widely used in the fields of photocatalytic degradation,hydrogen production and CO2 reduction.However,the band gap of g-C3N4 and TiO2 is large,and the utilization of solar energy is low.At the same time,there is a complex phenomenon of light generating electron hole pair,which restricts the wide application of materials in the field of photocatalysis.The band gap of oxide material Bi2O3 is located at 2.1-2.8 eV,and has a response in the visible region.In order to broaden the optical absorption capacity of g-C3N4 and TiO2 materials and promote the separation of photoelectron hole pairs,this paper uses g-C3N4 and TiO2 as the matrix material,and composite them with Bi2O3,and characterizing the morphology,physico chemical properties and photocatalytic properties of the composites,and studies the photocatalytic degradation and hydrogen production performance.The main contents of this paper are as follows:(1)Bi2O3/g-C3N4 composites were prepared by in situ calcining method and analyzed by X ray diffractometer(XRD),field emission electron microscope(SEM),ultraviolet visible diffuse reflectance spectroscopy(UV-vis DRS),fluorescence spectroscopy(PL)and other instruments.XRD analysis showed that the introduction of Bi2O3 material did not change the crystal structure of g-C3N4 matrix.SEM and TEM results showed that Bi2O3 and g-C3N4 formed the heterojunction interface.DRS analysis found that Bi2O3 increased the optical absorption capacity at 400-500 nm.The degradation of methylene blue dye under visible light showed that the degradation rate of 1%Bi2O3/g-C3N4 in 40 min was 97%,which was significantly better than that of pure phase Bi2O3(58%)and g-C3N4(48%).The experimental results of free group capture show that three active groups(h+),superoxide free radical(·02’)and hydroxyl radical(OH)play a role in the degradation system at the same time.The structural relationship shows that the activity of composite materials is improved because Z type heteroj unction between Bi2O3 and g-C3N4 promotes the separation of electron hole pairs.(2)Bi2O3-QDs-TiO2 composites were prepared by impregnation and high temperature calcination,and the phase structure,microstructure and absorbability of the materials were characterized by XRD,TEM,HRTEM,UV-vis DRS,X ray electron spectroscopy(XPS)and other instruments.The results of XRD analysis showed that Bi2O3-QDs did not change the crystal structure of TiO2,and the analysis of XPS elements showed that there was a single Bi in the material,which was formed by the reduction of Bi2O3-QDs by photoelectron.The results of TEM and HRTEM show that the grain sizes of TiO2 and Bi2O3 are 20-65 nm and 2-3 nm,respectively,and Bi2O3 is very good on TiO2.The results of hydrogen production in glycerol/aqueous solution showed that the hydrogen production of 1%Bi2O3-QDs-TiO2 was 920 umolh-1g-1,which was 72 times of that of pure phase TiO2(12.6 umolh-g-1).