Synthesis of Fe3O4-coated silica aerogel nanocomposites

Fe3O4:SiO2 nanocomposite powders were synthesized by a two-step process, which included the precipitation of FeCl2 and FeCl3 and the gelation of silicic acid solution derived from water glass. At first, Fe3O4 nanoparticles having a crystallite size of 20 nm were obtained by controlling the ratio of Fe (II) and Fe (III) precursors. In the second step, Fe3O4 particles were embedded in SiO2 matrix by the hydrolysis and subsequent condensation of the silicic acid solution containing Fe3O4 particles. It was found that the Fe3O4 nanoparticles homogenously disperse in the SiO2 matrix. The Fe3O4:SiO2 nanocomposite exhibited an enhanced thermal stability against oxidation compared with pure Fe3O4. FT-IR analysis indicates the presence of the Si—O—Fe bond in the Fe3O4:SiO2 (1:10, mole fraction) nanocomposite.