The Synthesis And Photocatalytic Properties Of Bismuth Oxide/Bismuth Ferrite Composites

Since the 21 st century,the process of urbanization has accelerated,and the problems of environmental pollution and energy shortages have become more and more serious.Semiconductor-based photocatalytic technology is one of the effective ways to solve energy and environmental problems.However,in practical applications,semiconductor photocatalysts have the disadvantages of low utilization rate of sunlight,poor stability,and difficulty in recycling.Therefore,the development of a new type of stable visible-light photocatalyst which can be recovered by magneticity has great significance.Because of the unique electronic structure,better photocatalytic performance,safety and non-toxic advantages,bismuth-based semiconductor materials is a very promising photocatalyst.And,China's bismuth is rich in resources while the development and utilization of bismuth-based materials are still in the initial stage.Therefore,the design of cheap and efficient bismuth-based semiconductor photocatalyst for environmental management has a good development prospects.In this paper,the Bi@BiFe-glycolate with a hollow structure is prepared by a simple one-pot solvothermal method.The formation process of the structure is studied by SEM,XRD,TEM and other methods,and the "swallow-spit mechanism" based on "Ostwald Ripening" was proposed.Then,Bi₂O₃/BiFe O₃ composite photocatalyst is prepared by heat-treating Bi@BiFe-glycolate precursors under air conditions.Under the conditions of acidic and visible light,the catalyst can completely degrade rhodamine B in 20 min.Compared with the pure phase Bi₂O₃ and BiFeO₃,the performance has been greatly improved.There are two main reasons: the first is the enhancement of visible light absorption;the second is the construction of heterojunction,which can reduce the recombination of electron-hole pairs,and is beneficial to the effective separation of photogenerated carriers.Then,the hollow Bi₂O_2.33/Bi₂O₃/BiFe O₃ composite photocatalyst is prepared by heat-treating Bi@BiFe-glycolate precursor under anoxic conditions.The results of the performance test showed that the photocatalyst can completely degrade rhodamine B under the same conditions in 15 min.The reason for the improvement of the performance is mainly due to the construction of Bi₂O_2.33/Bi₂O₃/BiFe O₃ three-phase heterojunction,which further improves the separation efficiency of the carrier.Free radical capture experiments show that in the photocatalytic degradation process,h+ play the major role.Cycle degradation experiments demonstrate that both Bi₂O₃/BiFe O₃ composite photocatalyst and Bi₂O_2.33/Bi₂O₃/BiFe O₃ three-phase composite photocatalyst have good cycle stability.On the other hand,the magnetic tests show that both of them have good soft ferromagnetic properties and can be magnetically recovered by applying an external magnetic field.