Preparation and characterization of mesoporous TiO2 particles by modified sol-gel method using ionic liquids

Synthesis of mesoporous TiO2 particles using ionic liquid (1L)-assisted sol-gel method was investigated. The prepared TiO2, particles using water immiscible room temperature ionic liquid, [Bmim][PF6], as an effective templating material had good structural properties including high surface area, stable crystal structure, controlled porosity and tailor-designed pore size distribution. Due to the unique properties of the ionic liquid, including zero vapor pressure and water-immiscibility, TiO2, particles with the anatase crystal phase were formed after the extraction of organic solvents without further heat treatment at high temperature. Especially, it was found that the strength of the hydrogen bonds on the anion part of ionic liquid with water was essential factor to form this mesoporous structure of TiO2 particles. The mechanism for the formation of these nanostructured TiO2, particles is an effective aggregation of the TiO2 particles with a self-assembled ionic liquid. Moreover, the length of alkyl group on the cation part of ionic liquid could determine the pore size and volume of TiO2 particles. Among the ionic liquids, it was found that 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim][PF6]) was the most effective ionic liquid to prepare mesoporous TiO2, particles. (c) 2005 Elsevier Inc. All rights reserved.