Formation mechanism of Fe2O3 hollow fibers by direct annealing of the electrospun composite fibers and their magnetic, electrochemical properties

Fe2O3 hollow fibers have been fabricated by direct annealing electrospun polyvinylpyrrolidone (PVP)/Fe(NO3)(3) composite nanofibers. In this approach, composite fibers were firstly synthesized by electrospinning PVP/Fe(NO3)(3) solution, and then calcined at high temperature with an appropriate heating rate to form hollow Fe2O3 fibers. The solvent composition, the addition amount of Fe(NO3)(3)center dot 9H(2)O and PVP, and the heating rate have important influences on the morphologies of Fe2O3 fibers. Morphologies of Fe2O3 could be tuned from solid belt to hollow belts and hollow fibers by controlling appropriate preparation conditions. The crystal structure, morphology, surface composition, magnetic and electrochemical properties of the Fe2O3 hollow fibers were investigated by using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, SQUID magnetometry and cyclic voltammetry, respectively.