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Thermal evolution of mesoporous titania prepared by CO2 supercritical extraction

Tursiloadi, Silvester and Yamanaka, Yu and Hirashima, Hiroshi (2006) Thermal evolution of mesoporous titania prepared by CO2 supercritical extraction. J Sol-Gel Sci Techn, 38 . pp. 5-12.

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Abstract

Porous anatase is attractive because of its notable photo-electronic properties. Titania wet gel prepared by hydrolysis of Ti-alkoxide was immersed in the flow of supercritical CO2 at 60◦C and the solvent was extracted (aerogel). Mesoporous TiO2 consisting of anatase nano-particles, about 5 nm in diameter, have been obtained. Thermal evolution of the microstructure of the aerogel was evaluated by TGA-DTA, N2 adsorption, TEM and XRD, and discussed in comparison with that of the corresponding xerogel. The diffraction peaks of anatase were found for the as-extracted gel while the xerogel dried at 90◦C was amorphous. After calcination at 600◦C, the average pore size of the aerogel, about 20 nm in diameter, was 4 times larger than that of the xerogel, and the pore volume, about 0.35 cm3 g−1, and the specific surface area, about 60 m2 g−1, were 2 times larger than those of the xerogel. XRD peaks of rutile have been found after calcination at 600◦C. The particle sizes of anatase and rutile are about 13 and 25 nm in diameter, respectively. The surface morphology of TiO2 nano-particles has been discussed in terms of their surface fractal dimensions estimated from the N2 gas adsorption isotherms.

Item Type:Article
Subjects:Material Science > Nanostructured materials
ID Code:4998
Deposited By:CSMNT
Deposited On:17 Apr 2009 08:30
Last Modified:17 Apr 2009 08:30

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