Abstract
TiO2 nanocrystalline thin films were prepared with spin coating by using sols deriving from titanium tetraisopropoxide (TTIP). The thin films were formed on soda lime glass and characterized by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, ellipsometry, and photoluminescence spectroscopy. The photocatalytic activity of the thin films was tested by the degradation of acid yellow 17 under UV irradiation. The results indicated that the photocatalytic activity was strongly correlated with the number of coatings and followed Langmuir-type kinetics. For thin films prepared by 0.1 M TTIP, the maximum specific photocatalytic activity occurred at 5 coatings with thickness of 93 ± 1 nm. A model was proposed to rationalize the dependence of the film thickness on the photocatalytic activity, which predicted the existence of an optimum film thickness.