Preparation, magnetic and electrochemical properties of xCuFe₂O₄/CuO composite microfibers

The nanocrystalline xCuFe₂O₄/CuO (x ≤ 50 %) composite microfibers with a fiber diameter about 0.5–2 μm, length of tens to hundreds of micrometers were prepared by the sol–gel process. The content of CuFe₂O₄ on the magnetic and electrochemical properties of CuFe₂O₄/CuO composite microfibers was investigated. The microfibers were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, vibrating sample magnetometer and X-ray photoelectron spectroscopy analysis. At the calcination temperature of 900 °C, with a content of copper ferrite phase about 10 %, the optimized porous composite microfibers are obtained. These composite microfibers show a typical soft magnetic property, and the specific saturation magnetization is related to the calcination temperature as well as CuFe₂O₄ content, with a steady M _r/M _s value of 0.64 at CuFe₂O₄ content (x) range from 10 to 50 %. The electrochemical properties of the as-prepared microfibers were investigated by cyclic voltammetry method, and the results show these composite microfibers are good electrode materials for supercapacitors. The 10 % CuFe₂O₄/CuO composite microfibers have the highest specific capacity of 81.7 F/g, with almost no decay after 200 cycles.