Preparation And Characterization Of Composite Photocatalyst On Bismuth Oxide/Graphene/Strontium Ferrite Modified With Samarium

Photocatalytic technology,which has the advantages of low energy consumption,high efficiency and environment-friendly,has good application prospects in the field of environmental pollution remediation.Bi₂O₃ is a new class of visible light photocatalytic material,has excellent photocatalytic properties and has attracted much attention in recent years.However,Bi₂O₃ is difficult to recycle and its electron-hole will recombine easily,andit can reduce the photocatalytic activity of the material.So,the application prospect of Bi₂O₃ in the treatment of water pollution still has obstruction.SrFe₁₂O₁₉ is considered to be an important permanent magnet due to its rich and inexpensive raw materials for preparation and its stable physical and chemical properties,but its use is limited due to its relatively weak magnetic properties.The development of a permanent magnet with high magnetic properties and a highly efficient photocatalytically active composite semiconductor photocatalyst has great significance for the practical application of Bi₂O₃ photocatalysts.In order to improve the magnetic properties of strontium ferrite,Sm³⁺-doped strontium ferrite were prepared by hydrothermal method.We studuied the influence of the doping content of Sm³⁺on the microstructure and magnetism of SrFe_12-xSm_xO₁₉（x=0⁰.5）.The material we prepared consists of two phases of SrFe₁₂O₁₉ andα-Fe₂O₃.Sm³⁺-doped strontium ferrite has the same grain size and morphology with hexagonal plated strontium ferrite,but it has less by-product ofα-Fe₂O₃ crystal phase than the undoped strontium ferrite.As the doping amount increases,the lattice constant c gradually increases.The saturation magnetization of the sample increases to the maximum value of 60.17 emu/g at x=0.4 and then decreases,and the coercivity increases with the increase of the Sm³⁺doping amount due to the substitution of 2b grain position of Fe³⁺by Sm³⁺and the reduction ofα-Fe₂O₃ crystal phase.It is found that the optimal molar ratio of Fe³⁺to Sr²⁺is 7:1.Bi₂O₃ and Bi₂O₃-GO composite photocatalysts were prepared by calcination and one-step method respectively.And which were characterized by XRD,SEM and UV-visDRS and so on.Two common crystal forms ofα-Bi₂O₃ andβ-Bi₂O₃ were selected for their preparation and comparison.The photocatalytic activity ofα-Bi₂O₃can be improved by optimizing the pH value of the preparation process,but the photocatalytic activity of the optimizedα-Bi₂O₃ is still poor than that ofβ-Bi₂O₃.Bi₂O₃-GO has the better photodegradation ability thanα-Bi₂O₃ andβ-Bi₂O₃.The content of GO has a great influence on the binary composite photocatalysts,and theβ-Bi₂O₃-GO has better composite effect thanα-Bi₂O₃-GO under simulated visible light irradiation.The photodegradation experiments ofβ-Bi₂O₃-GO shows that the photodegradation rate of RhB can reach 99%.Theβ-Bi₂O₃-SrFe_12-xSm_xO₁₉-GO ternary composite photocatalyst were prepaerd by precipitation and one-step method.The hexagonal flake-like SrFe_12-xSm_xO₁₉ was the carrier loaded with GO andβ-Bi₂O₃.When the compound amount of magnetic materials is small,the composites have good photocatalytic activity,which can still degrade RhB almost completely within 60 min.The nanocomposite has good ability of magnetic response,so it can be recycled under the influence of an external magnetic field.In addition,the nanocomposite has high photocatalytic activity,and the photodegradation rate of RhB can reach 82%at 60 minutes after recycling for 3 times.