Titania Nanocoating on MnCO3 Microspheres via Liquid-Phase Deposition for Fabrication of Template-Assisted Core–Shell- and Hollow-Structured Composites
2014
Lee, Hack-Keun | Sakemi, Daisuke | Selyanchyn, Roman | Lee, Cheal-Gyu | Lee, Seung-Woo
A novel class of core–shell- and hollow-structured MnCO₃/TiO₂ composites was synthesized by titania nanocoating on MnCO₃ microspheres via two-step liquid-phase deposition at room temperature. Morphological change from core–shell to hollow microparticles was possible in the prepared samples by controlling prereaction time of MnCO₃ and [NH₄]₂TiF₆. Upon the prereaction process, the core of the core–shell MnCO₃/TiO₂ became highly porous, and a honeycomb-like surface that resembled the orientation of self-assembled MnCO₃ nanocrystals was developed. The MnCO₃ core was completely removed after 6 h prereaction. Calcination at 600 °C resulted in the transformation of both core–shell- and hollow-structured composites to Mn₂O₃/TiO₂ anatase microspheres that retained their original morphologies. X-ray diffraction, field-emission scanning electron microscopy, Fourier transform infrared spectroscopy, transmission electron microscopy, and electron probe microanalysis were employed for microsphere characterization. As the first trial for application of the synthesized materials, solid-extraction of organics from aqueous media was examined using methylene blue (MB). Both types of Mn₂O₃/TiO₂ composites showed very fast adsorption of MB with high extraction values of 5.2 and 6.4 μmol g–¹ for the core–shell and hollow structures, respectively. Current work provides a new approach for facile fabrication of titania–metal oxide nanocomposites with unique morphological features and promising application possibilities.
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