Preparation Of Bismuth Bromide Nanomaterials And Its Photocatalytic Degradation Ability For Organic Dyes

Bismuth series photocatalysts have reduced the forbidden band width due to the participation of Bi6s and Bi6p orbitals in the valence band and conduction band of the semiconductor respectively,thus extending the light absorption range of bismuth series semiconductors to the visible region and avoiding the problem that Ti O₂ can only absorb ultraviolet light but not visible light.As an oxygen-rich derivative of Bi OBr,Bi₂₄O₃₁Br₁₀ has attracted the interest of many researchers because of its special layer sheet structure,suitable forbidden band width and good visible photocatalytic performance.The relatively high rate of photogenerated electron and hole complexation of Bi OBr limits its photocatalytic performance.Compounding with new materials（graphene,carbon nanotubes,quantum dot materials）,making lattice defects,forming Schottky barriers and constructing heterojunctions etc.Expanding the range of light absorption,increasing the utilisation of visible light,reducing its forbidden band width,promoting the separation and transport of photogenerated electrons and holes,and improving photocatalytic performance.The modification of bismuth bromide oxide(Bi₂₄O₃₁Br₁₀)by phosphorus sulphide quantum dots（PSQDs）not only increased the specific surface area of the catalyst,but also improved the visible light response of the whole photocatalyst,more importantly,PSQDS modified Bi₂₄O₃₁Br₁₀ formed a S-type heterojunction structure,and this heterostructure promoted the separation and transport of photogenerated electrons and holes,which could make The heterojunction has been used for the visible light photocatalytic degradation of organic dyes.The heterojunction has been characterised by various tests including XRD,HRTEM,TEM and XPS.Compared to pure Bi₂₄O₃₁Br₁₀,the composite can degrade rhodamine B（RhB）four times more efficiently,and it also degrades methyl orange（MO）and malachite green（MG）very well.Free radical capture experiments confirmed that superoxide radicals（·O₂^-）and hydroxyl radicals（·OH）are the main reactive oxygen species（ROS）components.The photocatalytic properties of bismuth bromide oxide(Bi₂₄O₃₁Br₁₀)were investigated using a solvothermal method and modified with starch.SEM,XRD,BET,PL and UV-Vis tests were used for characterisation.It was found that the addition of appropriate amount of starch could change the morphology of Bi₂₄O₃₁Br₁₀ to form a flower-shaped structure,which could increase the specific surface area of the sample,expand and simultaneously enhance the response of the photocatalyst to visible light,and effectively promote the separation and transfer of photogenerated carriers.The results showed that the photocatalytic degradation activity of bismuth bromide oxide(Bi₂₄O₃₁Br₁₀)was significantly improved after starch conditioning.