Synthesis And Photocatalytic Performance Of Floating BiOBr/graphene Aerogel-based Composites

With the improvement of people’s living standard and the development of industrial and agricultural technologie,the problem of water pollution has become increasingly serious.To purify the polluted water,photocatalytic technology came into being.The photocatalytic technology has attracted much attention of researchers due to its advantages of utilizing solar energy efficiently,high oxidation efficiency at room temperature,environmental protection,stability,easy recovery and thoroughly removing organic pollutants.In the treatment of large area of actual wastewater,the traditional powder photocatalyst has the problems of easy loss,difficult recovery,easy to cause secondary pollution and easy to sink to the bottom of the water when applied,resulting in insufficient utilization rate of light and oxygen and it needs constant stirring to make full use of visible light,etc.Therefore,a floating three-dimensional Bi OBr/graphene aerogel-based ternary heterojunction composite was prepared.On the one hand,this composite material can overcome the problems existing in the application of traditional powder materials,on the other hand,it can improve the photocatalytic performance of the three-dimensional binary heterojunction of Bi OBr/graphene aerogel material.The specific research contents and results are as follows:（1）Ultra-light floating cylindrical three-dimensional BiOBr/Bi₅O₇I/graphene aerogel（GA/Bi OBr/Bi₅O₇I）was successfully synthesized by simple one-step hydrothermal method.XRD,SEM,TEM,PL,UV-vis DRS and other means were used to characterize and analyze the composition,morphology and performance of the material.The prepared composite material exhibits a well-organized heterostructure,in which two bismuth-based photocatalysts with similar sizes are surrounded by a 3D reduced graphene oxide network.Under visible light irradiation,the best GA/Bi OBr/Bi₅O₇I composites exhibit the optimal separation efficiency of photogenerated electron-hole pairs and the best transfer efficiency of photogenerated carriers.The conductive 3D graphene aerogel provides a high-speed channel for separation and transfer of photogenerated carriers.The prepared ternary composite three-dimensional GA/Bi OBr/Bi₅O₇I photocatalyst is used for degradation of Rh B and inhibition of the growth of Microcystis aeruginosa with visible light.Experiments show that the highest rate of rhodamine B degradation of three-dimensional GA/Bi OBr/Bi₅O₇I is 2.7 times that of GA/Bi OBr,and the best photocatalytic efficiency of algae cell growth inhibition is 1.81 times that of GA/Bi OBr.The excellent floatability and stability of GA/Bi OBr/Bi₅O₇I materials make them easy to be recycled and reuse,which greatly improves the possibility of their practical application.（2）A series of 3D-BiOBr/TiO₂NWs graphene aerogel composites were synthesized by adjusting the molar ratio of Ti O₂NWs and Bi OBr.XRD,SEM,TEM,PL,UV-vis DRS and photoelectrochemical properties were characterized and analyzed.It is found that the three-dimensional structure is uniformly formed between Ti O₂NWs,Bi OBr and reduced graphene oxide.The addition of Ti O₂NWs forms a ternary heterojunction structure,which effectively accelerates the separation and transfer of photogenerated carriers.Under 180 minute visible light illumination,GBT3 with a molar ratio of 1:1 of Ti O₂NWs and Bi OBr show the strongest photocatalytic degradation activity of Rh B,and the degradation rate is 2.5 and 3.7 times that of GA/BiOBr and GA/TiO₂NWs,respectively.