科研之友
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摘要
Mesoporous zirconia with high surface area has been synthesized using self-assembling agarose gel as a template. Agarose gel was formed in the presence of aqueous zirconyl nitrate solutions followed by precipitation of zirconium (hydr)oxide in the gel framework. A porous zirconia structure is obtained by pyrolysis of agarose. Fourier transform infrared spectroscopy is employed to assess the agarose-zirconia precursor interaction. Changes in the C-O absorption bands indicate zirconium association with the OH groups of the agarose. Solid state C-13 NMR studies of the nanocomposite showed a shift in intensity from 70 to 75 ppm indicating conversion of similar to 7% of C-O-H to C-O-Zr. Scanning electron microscopy reveals that both agarose/zirconia nanocomposite and zirconia have similar morphological features as that of pure agarose gel confirming agarose templation. Phase transformation of zirconia from amorphous to tetragonal between 300 degrees C and 500 degrees C, and gradually into monoclinic phase up to 900 degrees C is observed using X-ray powder diffraction. Specific surface area and pore size distribution are determined using nitrogen adsorption, employing BET and BarrettJoynerHalenda methods, respectively. The specific surface area of porous zirconia after heat treatment at 500 degrees C was determined to be 86 m(2)/g, which reduced with increasing temperature to 13 m(2)/g above 900 degrees C. Transmission electron microscopy confirmed the hierarchical structure of porous zirconia.
- 出版日期2012-11
