Preparation And Photocatalytic Performance Of BiOBr/RGO-based Composites

BiOBr,a photocatalyst with a high response to visible light,has a unique tetragonal crystal structure and a relatively suitable band gap,making it a sustainable development in the field of visible light catalysis.However,its electron-hole recombination rate is extremely high,so it is key to solving this limitation that exploring a simple and feasible method can further improve its photocatalytic activity.At present,graphene is one of the most widely used carbon materials,which is attributed to its advantages of large theoretical specific surface area,high carrier mobility,strong adsorption and non-toxic and harmless.Therefore,when it is combined with BiOBr,it can become an effective strategy to improve this problem,and gradually improve the development of photocatalysts with high visible-light catalytic activity and high transfer efficiency.In this work,BiOBr with a 3D flower-like microsphere structure was loaded on RGO sheets by a simple hydrothermal method.The photo-generated electrons of BiOBr are easily captured by graphene,which promotes the separation of photogenerated electron hole pairs and obtains both adsorption and photocatalytic activity.The effects of visible light photocatalytic degradation ability of BiOBr/RGO composites with different doping mass percentages of RGO at different reaction times were evaluated by degradation of the target pollutant Rhodamine B aqueous solution.The photocatalytic reaction rate was characterized by kinetic analysis.The results reveal that BiOBr/RGO doped with 33% RGO has the best photocatalytic activity,the total removal rate can reach 93%,and its k_app value is 2.45 times that of pure BiOBr,which fully demonstrates its remarkable photocatalytic performance improve.However,the general photocatalyst materials are mostly in powders,and there are many obstacles in the practical application of recycling and cost issues.Therefore,in this work,BiOBr and Fe₃O₄/RGO were successfully heterojunction compounded to obtain a recyclable BiOBr/Fe₃O₄/RGO visible-light photocatalyst.The effect of different Fe₃O₄/RGO mass percentages of BiOBr/Fe₃O₄/RGO on Rh B degradation under different time conditions was investigated.The kinetics and the effect on the degradation of different dyes were also evaluated.Among them,BiOBr/Fe₃O₄/RGO with Fe₃O₄/RGO mass percentage of 56% showed the best removal capacity for rhodamine B under visible light irradiation,the total removal rate reached 96%.It is worth noting that its k_app value is 2.23 times that of pure BiOBr,and it also has a very high response to cationic dyes.Through a combination of characterization methods,experiments and theoretical calculations,it is proposed that Fe₃O₄ doped RGO and BiOBr form an n-type Schottky contact.Further,BiOBr/Fe₃O₄/RGO composites with the permanent-magnetism can be recovered and reused easily by external magnetic field and maintain a total removal efficiency of 90% after four times.