Effect of deposition methods on the properties of photocatalytic TiO2thin films prepared by spray pyrolysis and magnetron sputtering

Titanium dioxide thin films were deposited by DC reactive magnetron sputtering and spray pyrolysis methods onto glass and glass coated with fluorine doped tin oxide (FTO). The films were characterized by x-ray diffraction, scanning electron microscopy, atomic force microscopy and UV–visible spectroscopy. For films deposited by the sputtering technique we have studied the effect of the total pressure of an Ar–O 2 mixture on the substrate properties, on the deposition rate, phase composition, crystallinity, surface morphology and on the photocatalytic properties. Also transparent TiO 2 thin films have been prepared by spray pyrolysis using a low concentration of titanium precursor with different substrate temperatures. At higher substrate temperatures the films were polycrystalline in the anatase phase; at lower substrate temperatures the films presented an amorphous configuration. The photocatalytic properties of TiO 2 thin films were tested with the degradation methylene blue under UV light irradiation. The higher degradation rates were reached for films prepared by spray pyrolysis with a substrate temperature close to 400 °C, and for a high total pressure (16 mTorr) for films deposited by DC magnetron sputtering.