Synthesis and microsructure of a novel TiO₂ aerogel-TiO₂ nanowire composite

TiO₂ aerogel-10 mol% TiO₂ nanowire composite was prepared by a sol-gel technique with the addition of TiO₂ nanowires to TiO₂ sol, followed by supercritical drying in CO₂. TiO₂ nanowires (anatase with minor rutile phases) as dispersoid were prepared by a hydrothermal process followed by calcination in air at 600°C. The TiO₂ nanowires were dispersed in a 2-propanol/H₂O/HNO₂ solution, and the mixture was added drop by drop to a tetrabutyl orthotitanate [i.e. Ti (IV) n-butoxide] solution in 2-propanol. After gelation, the TiO₂ alcogel-TiO₂ nanowire composite was dried in supercritical CO₂ to obtain the final, TiO₂ aerogel-TiO₂ nanowire composite. TEM analysis revealed that a unique "nanowire network" structure was formed within the mesoporous aerogel matrix. The aerogel-TiO₂ nanowire composite had a relatively large surface area 427 m²/g, with mesopores ∼16 nm in diameter and a pore of volume of 1.63 cm³/g.