Preparation And Photocatalytic Activity Of Composite Photocatalysts Based On Bismuth Oxides

In this dissertation,a series of bismuth oxides were prepared and modified by different methods to improve the phtocatalytic activity.The properties of these materials were characterized by XRD,SEM,TEM,FT-IR,XPS,BET,UV-Vis DRS and PL.Then,Rhodamine B?RhB?,methyllene blue?MB?,methyl orange?MO?and phenol were used as the simulated pollution sources to explore the photocatalytic properties of the samples.Combine their characterization and free radical quenching experiments to explore their catalytic mechanism.The main contents can be divided into three parts as followings:1.g-C₃N₄/BiOI binary compound was prepared by chemical precipitation,then change the different molar ratio of g-C₃N₄,BiOI and AgPO₄,make the AgPO₄ particles deposit on the g-C₃N₄/BiOI to form g-C₃N₄/BiOI/AgPO₄ composite photocatalysts.They were characterized via XRD,SEM,EDS and FT-IR and so on.By degrading RhB and MO to evaluate their photocatalytic properties,the result showed that the photocatalytic performance of the ternary complexes obtained big enhancement compared with the compounds.It may be that AgPO₄ acts as an electron medium in the composite to accelerate the transfer rate of carriers.The stability of the material was evaluated by repeated experiments.The possible mechanism of degradation was initially proposed through free radical capture experiments.It was found that h⁺was the main active material,then·O₂^-times,·OH was the last.2.The metal Bi particles were deposited on g-C₃N₄/BiOI composite via solvothermal method to form g-C₃N₄/BiOI/Bi composite photocatalyst with different mass ratios of-C₃N₄and BiOI.The phases,structure and morphology of the samples were characterized.By degrading RhB under visible light found that the photocatalytic properties of the composites were improved over that of the individual compounds.Then the stability of the material was evaluated by repeated experiments.The possible mechanism of degradation was initially proposed through free radical capture experiments.It was found that h⁺was the main active material.3.The?BiO?₂CO₃/g-C₃N₄ composite was synthesized by hydrothermal method.The result of SEM was that flower-like microspheres of?BiO?₂CO₃ were dispersed on the bulk g-C₃N₄ uniformly.Through the adsorption experiment for MB under dark conditions,it was found that the adsorption capacity and the concentration dye showed a good linear relationship.After fitting different adsorption models,the adsorption of MB on the?BiO?₂CO₃/g-C₃N₄ composite material was mainly Freundlich adsorption isotherm model.It indicated the photocatalyst showed a non-uniform multilayer adsorption.The adsorption stability of the complex was evaluated by repeated experiments.Selective experiments showed that the complex had the best adsorption effect on positively charged cationic dyes.After that,the degradation of MB under visible light was used to test its photocatalytic performance.It was found that the photocatalytic performance of the binary complex was significantly improved compared to the single compound.The phtocatalytic stability of the material was evaluated by repeated experiments.The possible mechanism of degradation was initially proposed through free radical capture experiments.It was found that h⁺and·OH were both the main active material.