Ultrathin hematite and goethite-hematite core-shell nanorods and composite nanowires by electrospinning
S. Cavaliere-Jaricot, A. Brioude, P. Miele
LMI-UniversitÚ de Lyon 1, FR
Keywords: nanorods, iron oxide, core-shell, nanocomposite, electrospinning
Abstract:Hematite (alpha-Fe2O3) is an environmentally friendly, low cost, high resistant to corrosion and versatile material with semiconducting properties. Due to such stability and electronic properties, this oxide has applications in several fields as catalyst, photocatalyst, photoelectrode, battery electrode, gas sensor, pigment and magnetic material. 1D alpha-Fe2O3 nanorods with ultrathin diameter (10 nm) and length between 100 to 200 nm were synthesized in aqueous solution at low temperature with a simple method based on the oxidation of Fe3O4 nanoparticles at acidic pH, without using surfactants. HRTEM also showed the presence of core-shell structures. The core phase is goethite (alpha-FeOOH) with the typical d(110)=4.18┼ interplanar distance and the shell is composed of hematite layers with the typical d(104)=2.703 ┼ interplanar distance. It is likely that the formation mechanism of the core-shell structures involves the heterogeneous nucleation of hematite on initially precipitated goethite cores. For thinner nanorods, we can assume that the goethite phase has been totally transformed into hematite one. Optical characterization of such 1D nanostructures was performed by Raman and UV-vis spectroscopy and will be furthermore discussed. Such nanomaterials are incorporated in a polymer matrix and composite nanowires (with possible applications in gas sensing and depollution) are obtained by electrospinning.