Preparation,Magnetic Properties And Application Of One-Dimensional Magnetic Composite Fabricated By Electrospinning

One-dimensional magnetic nanomaterials show various special physical effects than granular nanometers due to their high aspect ratio.Therefore,they have become an important research topic in the field of nanomaterials.Simple,controllable and low cost method as well as the good quality of obtained products are required in application.Electrospinning has been applied in the preparation of many one-dimensional nanostructured materials,such as nanotubes,nanowires and side-by-side nanowires due to its simple method and controllable preparation process.In this paper,CoFe₂O₄/SrFe₁₂O₁₉ composite magnetic nanowire materials and CoFe₂O₄/TiO₂composite photocatalytic materials were prepared by uniaxial and parallel-axial electrospinning techniques combined with post-heat treatment,and their microstructure and magnetism were systematically studied.Finally,we explore the application of CoFe₂O₄/TiO₂ nanowires composite in the degradation of organic dyes.The main research results are summarized as follows:1.SrFe₁₂O₁₉/CoFe₂O₄ composite nanowires with different molar ratios were prepared by uniaxial electrospinning,and their magnetic properties were systematically characterized.The results show that with the increase of the proportion of SrFe₁₂O₁₉,the number of hexagonal nanoparticles on the surface of the nanowires increases gradually,and the magnetic properties also change accordingly.The saturation magnetization（Ms）of the sample decreases monotonically while the coercivity increases with the increase of SrFe₁₂O₁₉ ratio.2.SrFe₁₂O₁₉/CoFe₂O₄ composite magnetic nanotubes were prepared by uniaxial electrospinning and annealing at different temperatures.It is found that all the samples have good crystallization,high purity and one-dimensional structure,in which the nanotube structure was formed after heat treatment at 800℃and 900℃.Different annealing temperatures have important effects on the distribution of CoFe₂O₄ and SrFe₁₂O₁₉,thus affecting the magnetic exchange coupling.With the increase of heat treatment temperature,saturation magnetization（M_S）decreases monotonically while coercivity（H_C）increases monotonically.3.SrFe₁₂O₁₉/CoFe₂O₄ side-by-side nanowires were prepared by parallel axial electrospinning at 800℃,900℃and 1000℃.X-ray diffractometry（XRD）,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,Lab RAM Aramis（Lab RAM HR Evolution）and vibrating sample magnetometer（VSM）were used to characterize and analyze the magnetic properties of the samples.The result shows that the samples all have the structure of side-by-side nanowires with good crystallinity and purity.The hysteresis loops all show similar single-phase magnetic behavior,indicating that there is a strong exchange coupling between the two phases.The coercivity increases with the increase of annealing temperature.4.A series of CoFe₂O₄/TiO₂ composite nanowires were successfully prepared by parallel axial electrospinning combined with post-heat treatment.Through the study of their microstructure,phase composition,light response characteristics,room temperature magnetic properties and photocatalytic properties,we found that the composite nanowires sintered at 500℃have obvious side-by-side structure.As the sintering temperature rises to 900℃,the side-by-side structure is destroyed,and the composite nano-chain particle structure composed of CoFe₂O₄ and TiO₂ is formed.Compared with the photocatalytic performance of the three samples,the composite photocatalytic material sintered at 500℃has the best photodegradation effect for bromocresol green,because its heterogeneous structure interface can effectively prevent the combination of electron holes and photogenerated electrons,so that the good photocatalytic activity is obtained.At the same time,based on the ferromagnetic characteristics of CoFe₂O₄,it can be effectively separated from water by external magnetic field.