Synthesis and electrochemical properties of biporous α-fe ₂o₃ superstructures

Biporous microsphere, flower and concaved cuboctahedrans like α-Fe2O3 superstructures have been synthesized by using a new synthetic method. Hydrothermal reaction of ferric chloride with potassium thiocyanate at 200 C yields self-assembled microsphere, flower, and concaved cuboctahedrans like intermediates in ethanol, water:ethanol (1:1) mixed solvent and in water, respectively. These intermediates were further converted into corresponding α-Fe₂O₃ in a thermal decomposition process at 600 C under oxygen atmospheric conditions. The influence of solvent, hydrothermal temperature, and concentration of iron precursors on the intermediate morphology was studied, and the growth mechanism has also been proposed. The synthesized intermediates and α- Fe₂O₃ were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HR-TEM) and nitrogen adsorption analysis. The FE-SEM results indicated formation of biporous flowerlike morphology. The electrochemical properties of the flowerlike α- Fe₂O₃ electrodes in a Li-ion battery have been investigated. Plausible formation mechanisms of these intermediates were proposed.