Study On The Synthesis And Photocatalytic Properties Of Nonmetal Doped Bismuth Chloride Oxide

Nowadays,increasingly serious environmental pollution has become one of the main factors restricting social development.Semiconductor photocatalysts have attracted more attention in environmental purification because of their clean,simple,and efficient characteristics.Among them,bismuth oxychloride（BiOCl）has high photo-corrosion stability and unique layered tetragonal martensite structure,which has been widely concerned in scientific research and practical applications.Its layered structure consists of[Bi₂O₂]²⁺layer and Cl^-layer connected by an internal electrostatic field.This internal electrostatic field is conducive to the formation of dipoles and can effectively separate the electron-hole pairs,so that it has a high Photocatalytic activity.However,because its wide bandgap is only responsive to ultraviolet light,at the same time,photoinduced carriers have a high recombination rate,which greatly limits the practical application.Therefore,researchers have explored many methods to improve the photocatalytic performance of BiOCl catalysts,such as semiconductor recombination,precious metal deposition,ion doping,surface modification,and photosensitization.In this thesis,two different shapes of BiOCl（flower ball and flake）were prepared and doped and modified with non-metallic elements.First,a flake BiOCl photocatalyst was successfully prepared by a one-step hydrothermal method.As a source of iodine,potassium iodide（KI）was used to prepare iodine（I）doped bismuth oxychloride（BiOCl）photocatalyst.Rhodamine-B（Rh B）was subjected to photocatalytic degradation under visible light irradiation,and the photocatalytic performance of BiOCl photocatalysts with different iodine dosages was evaluated.The results showed that the iodine（I）doped bismuth oxychloride（BiOCl）photocatalyst showed the best photocatalytic performance when the doping amount of iodine was 4%,and the degradation rate of Rh B could reach 99%at 45 min.This is mainly because iodine doping promotes the effective separation of electron-hole pairs,narrows the band gap,increases the absorption range of visible light,and thus enhances the photocatalytic activity of BiOCl.Secondly,a bismuth oxychloride（BiOCl）photocatalyst doped with sulfur（S）was prepared by using hydrothermal method with thiourea as the sulfur source.The photocatalytic performance of the photocatalyst was evaluated by degrading rhodamine-B（Rh B）.The results show that the bismuth oxychloride（BiOCl）photocatalyst with 2%sulfur（S）doping content has the best photocatalytic performance,and the degradation rate of Rh B can reach 99%in 45min.Finally,the microsphere-shaped BiOCl photocatalyst was prepared by hydrothermal method with the reactants and solvents changed.Similarly,using thiourea as the sulfur source,sulfur（S）doped bismuth oxychloride（BiOCl）photocatalyst was prepared.The photocatalytic performance of the catalyst was determined by degrading rhodamine-B（Rh B）under visible light.The experimental results show that bismuth oxychloride（BiOCl）doped with 6%sulfur（S）has the best photocatalytic activity.When the photocatalytic reaction is carried out for 12min,the degradation rate can reach 99%.The doping of sulfur（S）element increases the specific surface area of the catalyst,expands the absorption range of visible light,and improves the separation efficiency of photogenerated electron-hole pairs,resulting in the improvement of photocatalytic performance.In addition,the sulfur（S）doped bismuth oxychloride（BiOCl）photocatalyst showed excellent recyclability and stability.