Preparation of high surface area titania (TiO2) films and powders using particulate sol–gel route aided by polymeric fugitive agents

High specific surface area (SSA) nanocrystalline powders and dip-coated TiO2 films have been prepared by particulate sol–gel route aided with polymeric fugitive agents (PFA), namely trehalose dihydrate (THD), polyethylene glycol (PEG6000) and hydroxypropyl cellulose (HPC). Powders obtained without PFA, heat-treated at 160 °C show a SSA of 181 m2/g, a value that could be increased up to 271 and 223 m2/g for samples heat-treated at 300 °C when PEG6000 and HPC were used, respectively, whereas SSA of 201 m2/g were achieved by using THD and subsequence heat-treating at 500 °C. Such surface area is one of the highest reported in the literature under these conditions. Crystallite sizes vary from 1 nm for as-produced powders up to 4 nm for powders heat-treated at 600 °C. It was found that crystallite size, microstructure, specific surface area and phase transformation are strongly dependent upon the PFA/TiO2 ratio and annealing temperature. Films produced under optimised conditions showed excellent microstructural properties for gas sensing applications.