(217a) Preparation and Characterization of Zirconia Aerogels By a Non-Alkoxide Sol-Gel Method

Zirconia(ZrO₂) aerogels have attracted a lot of attention in recent years as a result of their unique structures and wide potential applications inheat insulation, catalysts, catalyst supports, dye-sensitized solar cellsand solid oxide fuel cells (SOFCs).Thus, extensive effort has been made to synthesis zirconia aerogels.However, ZrO₂monolithic aerogels are difficult to getbecause of high sensitivity ofits precursors to various sol-gel parameters.This work focuses oncontrolling the hydrolysis-condensation of zirconium inorganic salt withcomplexing agent and propylene oxide(PO). Monolithic gels, not precipitates, are easily formed in the mixed solution of distilled water and ethanol. After removing the solvent in gels by supercritical drying in ethanol, we willget the ZrO₂ monolithic aerogelswith low density and high porosity.The resulting aerogels are calcined at different temperatures for different time. Then, The morphology and structures of as-prepared and calcined aerogels arecharacterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction(XRD), raman spectroscopy, BET surface area analysis, thermogravimetric and differential scanning calorimetry analysis (TG-DSC).It is found that the BET surface area of as-prepared aerogels is 407m²/g. After calcined at 550℃ for 2h, the crystal form of as-prepared aerogels will transform to tetragonal phase from amorphous phase.