Synthesis and electrochemical properties of hierarchically porous Fe2O3

Porous Fe2O3 with hierarchical structure was obtained by a two-step template-free synthesis route. Brick-shaped ironic oxalate precursor in micrometer size was first synthesized by a hydrothermal process using (NH4)2SO4 · FeSO4 · 6H2O and K2C2O4 · H2O as raw materials. Then porous iron oxide with well retained brick-shape was obtained by a decomposition process under precisely controlled annealing condition. Morphology and structure of the as-prepared products were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), thermo-gravimetric/differential thermal (TG-DTA) and N2 adsorption-desorption measurements. The electrochemical properties were performed by galvanostatic cell cycling. It revealed that the pore structure can be tailored by the annealing condition and the crystallinity can be tuned by the solvent system. Product with porous structure and low crystallinity exhibited storage capacity of 634 mA h g−1 during the first cycle and efficiency of over 90% after 20 cycles.