Silica layer was deposited on the spherical Co3O4 particles, which were prepared by the thermal decomposition of cobalt nitrate, by the hydrolysis and condensation of tetraethylorthosilicate (TEOS) in the presence of cetyltrimethylammonium bromide (CTAB) in alcohol (methanol, ethanol, propanol or butanol). The products were characterized by X-ray diffraction (XRD), scanning and transmission electron microscopies (SEM and TEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric/differential thermal analysis (TG-DTA), UV–vis absorption spectroscopy, and vibrating sample magnetization (VSM). The result showed that the spherical Co3O4 particles with the average diameter of 242 nm were coated with silica layer (the thickness of 12–27 nm). The thickness of the silica shell varied depending on alcohols, methanol gave thicker silica shell than ethanol, butanol and propanol. Irrespective of the thickness of the silica shell, all the present Co3O4@SiO2 core-shell particles showed a soft ferromagnetic with narrow hysteresis loops, not much different from that of pristine Co3O4, suggesting possible applications as magnetic particles with modified surface properties. The core-shell particles were stable in acidic solution (pH = 1) to extend the potential of magnetic Co3O4.
|ジャーナル||Colloids and Surfaces A: Physicochemical and Engineering Aspects|
|出版ステータス||Published - 2016 12月 20|
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