The alpha-Fe(2)O(3) with various morphologies has been successfully synthesized via an ionic liquid-assisted hydrothermal synthetic method. The samples are characterized by X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscope (FE-SEM), transmission electron microscopy, and high-resolution transmission electron microscopy. The results indicate that the as-prepared samples are alpha-Fe(2)O(3) nanoparticles, mesoporous hollow microspheres, microcubes, and porous nanorods. The effects of the ionic liquid 1-n-butyl-3-methylimidazolium chloride ([bmim][Cl]) on the formation of the alpha-Fe(2)O(3) with various morphologies have been investigated systematically. The proposed formation mechanisms have also been investigated on the basis of a series of FE-SEM studies of the products obtained at different durations. Because of the unique porous structure, the potential application in water treatment of the alpha-Fe(2)O(3) porous nanorods was investigated. The UV-vis measurements suggest that the as-synthesized pure alpha-Fe(2)O(3) with various morphologies possess different optical properties depending on the shape and size of the samples. The magnetic hysteresis measurements indicate the interesting magnetic property evolution in the as-prepared alpha-Fe(2)O(3) samples, which is attributed to the superstructure or the shape anisotropy of the samples. This method is expected to be a useful technique for controlling the diverse shapes of crystalline inorganic materials for a variety of applications, such as sensors, gas and heavy metal ion adsorbents, catalytic fields, hydrogen and Li ion storage, and controlled drug delivery, etc.

The size- and shape-controlled fabrication of α-Fe2O3 has been successfully realized via a faicle template-free hydrothermal route, only simply changing reaction time and solvent used. The formation mechanisms of various nanostructures are proposed and the controlling factors on the morphology of the final product are also discussed. Furthermore, magnetic hysteresis measurements demonstrate that the as-obtained α-Fe2O3 nanostructures show structure-dependent magnetic properties. And the as-obtained α-Fe2O3 nanopolyhedra exhibits ultrahigh reversible capacity, and excellent capacity retention over 20 cycles. It is expected that the adjustable magnetic properties and high discharge capacity of the as-prepared samples make them useful with potential applications in magnetic nanodevices and high-energy batteries.

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