Study On Morphology Regulation And Photocatalytic Performance Of BiOBr And Its Composite Semiconductor Materials

As a class of semiconductor photocatalysts with wide application and good photocatalytic efficiency,bismuth oxybromide has been studied for a long time.Among them,BiOBr,as a member of bismuth oxyhalide,is more favored as a research object because of its mild synthesis conditions,simple structure and easy modification.However,when BiOBr is fabricated with a uniform morphology,a main exposed surface with high catalytic activity,and as a precursor of a compound semiconductor catalyst,its performance is sometimes not greatly improved in practical applications,and the method is still lacking in innovation.In view of the above problems,in order to design a new BiOBr heterojunction with high catalytic performance morphology and crystal plane and a precursor BiOBr heterojunction with enhanced photo-generated electron-hole pair separation efficiency to improve the photocatalytic activity,BiOBr was used in this paper as the photocatalytic activity.The research object has been systematically explored,and the following results have been obtained.First,by analyzing the synthesis conditions of BiOBr and CNNTs,we found that both substances are easy to be fabricated in large quantities at low temperature,which provides a theoretical possibility for the successful recombination of the two to form new compound semiconductors.The BiOBr-CNNTs composite photocatalyst with efficient photocatalytic sterilization activity was successfully synthesized by chemical oxidative polymerization and in situ loading method.The inactivation efficiency of BiOBr-CNNTs against 10⁷CFU/m L E.coli was greatly improved under visible light.The plate counting method showed that it could inactivate about 6 Log₁₀ CFU/m L of large intestine within the experimental time（within 35 minutes）.Bacillus.Afterwards,through XPS,ESR spectral test and reactive oxygen species test on BiOBr-CNNTs,it was observed that the BiOBr-CNNTs formed by the successful composite formation of BiOBr and CNNTs induced by low temperature can generate a large number of oxygen vacancies,improve the charge separation efficiency,and effectively promote the generation of interfacial reactions.A large amount of active oxygen,so it has excellent photocatalytic performance and sterilization ability.At the same time,the experiments confirmed that h⁺,surface bounded·OH,·O₂^-and H₂O₂ were the main sterilization active substances,and the possible photocatalytic sterilization mechanism of BiOBr-CNNTs was explored.In addition,BiOBr-CNNTs still had strong antibacterial activity after five times of use,indicating that the compound semiconductor has good stability.Second,based on the special effect of temperature on semiconductors,by changing the synthesis temperature,we successfully prepared a product with strong catalytic degradation ability,uniform and specific morphology,and the main exposed crystal face is（110）by one-pot hydrothermal method and high-temperature calcination method.BiOBr nanosheets.After a series of characterization and performance tests,we found that BiOBr fabricated by hydrothermal calcination at 350°C has the narrowest forbidden band width and the largest light absorption range,which can fully utilize sunlight.In the tetracycline degradation experiment that does not affect the adsorption-desorption equilibrium state,the BiOBr fabricated by hydrothermal calcination at 350°C has the largest photocatalytic degradation activity,and can degrade more than 95%of tetracycline within 3 hours,which can achieve some environmental problems.standard.The good degradation performance also led us to further study and found that the active oxygen species h⁺,·O₂^-and H₂O₂ in the BiOBr were effective substances to promote photocatalytic degradation,and a reasonable reaction mechanism was established.In the fifth cycle experiment,the sample still maintains a very high degradation ability,indicating that the BiOBr has good stability and high reusability.