Preparation And Modification Of BiFeO₃ Nanofibers By Electrospining

With the development of science and technology, human’s needs and social wealth increase at the same time. With the expansion of industrial production, the source of high concertraton organic wastewater and PM2.5 increases day by day,which have brought serious pollution and harm to the environment. These pollution has brought serious threaten to human survival and development. Deveplopping an effective, simple and energy effcient means to solve the pollution problem. This is pressing problems of human society. Bismuth based materials have unique advantages in solving water polltion problems. The valence band and conduction band of the Bismuth based semiconductor is consisted of B6 S and B6 P. This kind of structure decreases the band gap of the bismuth based semiconductor and expands the light response range of the Bismuth based semiconductor to the field of visible light.Bismuth based semiconductor can make use of visible light to catalyze. Solar energy is a kind of stable non-pollution energy and the use of solar energy can effectively relieve the energy crisis of human beings.nanofibers prepared by electrospinning are highly expected for their high specific surface area, length-diameter ratio, porosity,easy to prepare and low cost. it can be industrialized and be highly expected by scientists. Series of ferrite bismuth powder and fiber were prepared by hydrothermal method and electrospinning method in this paper. The composition, morphology and microstructure of the fibers had been characterized by TG-DSC, FTIR, XRD, SEM,TEM and UV analysis. The application of bismuth ferrite was analyzed by the experiment of photocatalytic degradation of organic pollutants. The main conclusions of the paper are below:The Bi₂Fe₄O₉ and BiFeO₃ powder were successfully prepared by hydrothermal method. The Bi₂Fe₄O₉ powder particles are spherical size and the particle size is uniform.The diameter of it is around 75 nm.The powder particle size of BiFeO₃ is small and the size is approximately 50 nm.The forbidden band width of BiFeO₃ powder and Bi₂Fe₄O₉ powder is 2.18 ev and 2.2 ev. The catalytic dye degradation rate of BiFeO3 powder is 64%.The BiFeO₃ fiber precursor is prepared by the electrospinning technology and the fiber samples are calcined under different temperature. With the increase of sintering temperature, the inpurity phase gradually reduced,the characteristic peak of the ferrite bismuth gradually strengthened and the crystallinity increased. The grain size become bigger with the rising of sintering temperature.Under high temperature calcination,the surface of the fiber is roughness and present bamboo-like shape.Under low temperature calcination,the surface of bismuth fiber is smooth with uniform thickness. The diameter of ferrite bismuth fiber is about 220 nm. Under 550 ℃calcination, the sample has good crystallinity and relatively low band gap width.The dye degradation rate of it reaches 70%. Fibers have weak magnetic properties, which can be recycled in catalytic applications.The ferrite bismuth can be successfully modified by doping zinc ions.The smooth fiber surface become rough with modification.The optical performance test of modified fiber shows the presence of Zinc – O.The granular-shape zinc oxide is on the surface of the fiber.With the amount of zinc ions doping is 0.5% in ferrite bismuth fiber, fiber catalytic degradation rate reaches 83.1%. At this time,the optimal catalytic performance is best.