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In recent years, titanium dioxide (TiO2) with photocatalytic activity has received a great deal of attention because of its ability to detoxify environmental pollutants. Several physical and chemical techniques have been used to prepare titanium dioxide thin films. Among the various techniques, the relatively simple sol gel method is the most widely used because of its ability to obtain films with tailored properties on large, curved substrates, and also it is a low temperature process. In our study, the titanium dioxide porous films were deposited on glass slides by sol-gel technique; where, tetrabutylorthotitanate was used as a precursor and was hydrolyzed in a water/alcohol/amine mixture. Polyethylene glycol (PEG) was added to the coating solution as a structure-directing agent, and the films thus prepared were transparent, crack free. In this present investigation, titanium dioxide thin films were prepared with different PEG concentrations and with different numbers (2-8) of coatings to optimize the photocatalytic activity. The structural and optical characterizations of these films were made by X-ray diffraction (XRD) and UV-Vis spectroscopy, respectively. XRD patterns of all the titanium dioxide films confirmed the anatase structure. The surface morphology of the films were observed by atomic force microscope (AFM) and scanning electron microscope (SEM). The morphology of porous titanium dioxide thin films strongly depends on the concentration of the template (PEG). The decomposition of PEG during high temperature treatment is considered to be responsible for the generation of porous structure in the films as compared with titanium dioxide film without addition of the polymer. The photocatalytic activity of the titanium dioxide thin films was evaluated by the study of decomposition of methanol with the help of FTIR spectroscopy. It has been observed that the photocatalytic activity of the titanium dioxide thin films increases with the increase of the PEG concentrations as well as with the increase of the numbers of layers. The variation of photocatalytic activity with different PEG concentrations and different number of layers is interpreted in terms of different crystallinity, porosity and surface morphology. |