Synthesis and photocatalytic properties of dense and porous TiO2-anatase thin films prepared by sol–gel

Porous TiO2-anatase films were prepared by sol–gel route showing higher photocatalytic activity in degradation of trichloroethylene (TCE) in air compared to dense titania films. Titania sols were synthesized with and without a pore generating agent, polyethylene glycol (PEG), to evaluate the effect of porosity in the photocatalytic activity of the coatings. The films were deposited by dipping and sintered at different temperature and time. The characterisation was performed by profilometry, Fourier transform infrared spectroscopy (FTIR), grazing X-ray diffraction (GXRD) and field emision scan electron microscopy (FE-SEM), observing that anatase phase is obtained at temperatures as low as 350 °C. The maximum specific surface area (Ss = 43 m2/g) was obtained for coatings prepared from TiO2 sol with PEG and sintered at 400 °C. Porous TiO2-anatase films present TCE conversion around 20% higher than that of dense films. Porous volume, surface area and thickness of the coating play a key role in the photocatalytic activity. On the other side, variation in particle size seems not to be a critical parameter in the studied range.