Preparation And Characterization Of BiOBr-based Photocatalytic Materials

In recent years,semiconductor catalysis technology has attracted people's attention due to its broad application prospects in environmental management.Compared with traditional processing technology,photocatalytic materials have the advantages of economy,high efficiency and no secondary pollution.The ruthenium bromide photocatalytic material has a unique layered structure and good visible light absorption performance,which is beneficial to light trapping and photocarrier transport,enhances photocatalytic activity,and can modulate photocatalytic performance through interlayer molecular or ion changes.Therefore,it has become one of the hot spots in the field of photocatalytic materials research in the near future.However,low specific surface area,insufficient visible light utilization efficiency,and faster recombination of photogenerated electrons and holes limit its application.It has become an important research direction to explore a ruthenium bromide-based photocatalyst with high efficiency photo-generated charge separation/transmission rate.In this thesis,the photocatalytic properties of ruthenium bromide photocatalysts were studied by using bismuth bromate bismuth semiconductor materials as the main research object,from the aspect of morphology to improve the specific surface area and construct heterogeneous structure.(1)A modified cellulose fiber is prepared by a TEMPO oxidation method using a pulp board as a raw material.A BiOBr/modified cellulose composite photocatalyst was prepared by an in situ growth method.Taking full advantage of the three-dimensional network structure of cellulose and the high specific surface area,the disadvantage of lower adsorption of BiOBr semiconductor materials is improved.In addition,the surface of the modified cellulose has a weak electrical conductivity,which can promote the effective separation of the photogenerated electron holes of the composite photocatalyst,and effectively suppress the recombination thereof,thereby enhancing the photocatalytic activity.(2)BiOBr/BiOI/modified cellulose composite photocatalyst was prepared by in-situ synthesis.The BiOBr/BiOI heterostructure was constructed on the surface of the modified cellulose fiber by adjusting the molar ratio of Br to I.When the molar ratio of Br to I is 9:1,90% BiOBr/BiOI/modified cellulose composite photocatalyst has the highest photocatalytic activity.The special three-dimensional network structure gives the material a high specific surface area,which is beneficial to the adsorption capacity of organic pollutants.At the same time,through the construction of the BiOBr/BiOI heterostructure on the surface of the MC,the absorption of visible light by the composite photocatalytic coloring material is enhanced,the effective separation of photogenerated electron-hole pairs is promoted,and the recombination of photogenerated electron-hole pairs is inhibited.The photocatalytic activity of the composite photocatalyst is increased.In addition,photocatalytic cycle degradation experiments show that 90% BiOBr/BiOI/modified cellulose composite photocatalyst has high photocatalytic activity and stability for rhodamine B,fluorescein and tetracycline hydrochloride.(3)The conductive fiber network structure was constructed by adding conductive polyaniline PANI,and then BiOBr was loaded onto the conductive fiber by in-situ synthesis method.The PANI/BiOBr/MC composite photocatalytic material was successfully prepared.And when the amount of PANI is 0.2 g,the prepared composite photocatalytic material 0.2PANI/BiOBr/MC has the best photocatalytic activity.In this material,BiOBr exhibits microspheres assembled into nanosheets with a high specific surface area.The excellent photocatalytic activity can be attributed to the introduction of PANI,which is constructed into conductive fibers,which enhances the adsorption capacity of the composites to contaminants,and at the same time improves the photo-electron separation efficiency of the composites while suppressing the photo-electron-hole pair recombination.In addition,BiOBr exhibits microsphere shape,which can enhance the photogenerated electron separation efficiency to some extent.