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

Abstract

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)₃·9H₂O 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.