Characterization and Comparison of the Nanostructured Heterogenous TiO2/Al2O3 and TiO2 Films

Nano photo-catalyst coatings، exposed to high-energy photons، have the ability to remove toxic organic compounds from gaseous and aqueous environments. But these coatings، due to lower surface area، are less efficient than nanoparticles. Microstructure of these coatings should be modified in order to improve their efficiency. In this study، nanostructured TiO2/Al2O3 heterogeneous films were synthesized by the sol-gel method. Quartz sheets were used as the substrates، and Al2O3 and TiO2 sols were، in turn، deposited on these substrates by the spin coating method، respectively. The deposited layers were sintered at 800°C and 500°C، respectively. Crystallization of gamma-alumina and anatase phases was confirmed by X-ray diffraction (XRD). The average crystallite size of the anatase films was measured to be about 30 nm by using scanning electron microscopy (SEM). UV-vis absorption spectroscopy was used to calculate the energy gap، and based on the measured absorption wavelengths; the total gaps were calculated to be 3. 81 eV and 4. 47 eV، for TiO2 and TiO2/Al2O3 layers، respectively. The emission spectra obtained by the photoluminescence analysis were used to confirm the oxygen vacancy formation. Our results showed that، by the addition of Al2O3، neutral oxygen vacancies may be thermodynamically stable stabilized in TiO2.