Research On Preparation And Photocatalytic Properties Of Bi-based Materials

With the growth of the world’s population and the development of industry,the increasingly serious water pollution problem has become one of the most challenging problems in the world.As an sustainable green technology,semiconductor photocatalytic degradation has attracted much attention.As a new type of photocatalyst with suitable forbidden band width,good stability,and high-efficiency catalytic activity,bismuth-based photo-semiconductor catalysts have attracted more and more researchers’attention.However,in the application of pollutant degradation,an excellent photocatalyst should have a wide absorption spectrum,efficient charge separation ability,super redox ability,and excellent adsorption ability.For a single-component catalyst,these requirements cannot be met at the same time.Therefore,this paper aims to construct two heterojunction composite photocatalysts based on bismuth-based emiconductor catalysts to optimize the catalytic activity of them.The main works as follows:1.By simple in-situ crystallization method,Ti O₂（B）-Bi OBr heterojunction composite photocatalyst material was synthesized.In this catalyst,Ti O₂（B）is used as a template to make the size-reduced Bi OBr nanoplates grow on the surface in situ.The composite material retains the characteristics of Ti O₂（B）,so it has a large specific surface area and a suitable pore size distribution.There is a close interface contact between Ti O₂（B）and Bi OBr,which effectively promotes the transfer of photogenerated carriers between different materials.The catalyst,which has a strong dye-sensitized oxygen activation ability,can rapidly produce a large amount of superoxide radicals（·O₂^-）under the sensitization of rhodamine B（Rh B）.Therefore,Ti O₂（B）-Bi OBr exhibits excellent photocatalytic water treatment of various pollutants,while simultaneously removing rhodamine B（Rh B）,methyl orange（MO）,tetracycline hydrochloride（TH）and bisphenol A（BPA）,etc.pollutants with different properties in a mixed system,the reaction rate constants for the degradation of each pollutant are 4.7,1.4,23and16.4 times of the monomer Bi OBr respectively,and have excellent stability.2.Using KI to hydrothermally treat basic bismuth nitrate Bi₂O₂（OH）（NO₃）（BION）,the BION-Bi OI P-N heterojunction was synthesized in situ.Bi OI is grown on the surface of BION in situ,which accelerates the photo-generated electron-hole transfer ability and successfully expands its absorption range from ultraviolet to visible light.Efficient carrier separation and transfer and visible light absorption capacity make it significantly improve the catalytic activity of organic pollutants such as methylene（MB）and methyl orange（MO）under visible light,and still maintain good activity after multiple cycles.