Titania nanorods array homojunction with sub-stoichiometric TiO2 for enhanced methylene blue photodegradation

Abstract

TiO2 thin films are known to promote photodegradation of dyes and pollutants in water solution via heterogeneous photocatalysis. This ability is guided by the photoexcitation at wavelength corresponding to the bandgap energy. Recent studies showed that TiO2 vertically aligned nanorods array could improve surface area and electronical transfer properties. Combining this effect with an induced vacancy doped homojunction in TiO2 array could furthermore enhance the photochemical activity. In this thesis, titanium dioxide vertically aligned nanorods have been grown on the conductive side of a FTO glass, depositing with spin coating technique of a seed layer of colloidal TiO2 and a successive hydrothermal growth in acidic conditions at 150°C. Dried samples have been deposited via magnetron sputtering with 50 nm of TiOX at three different stoichiometries, tuning the oxygen concentration in sputtering argon atmosphere at 10%, 15% and 20% respectively. The thin films have been characterized by several techniques, such as FEG-SEM microscopy, X-Ray Diffraction and UV-Vis Sprectrophotometry for the bandgap analysis. Samples have then been employed as catalysts in the photodegradation of methylene blue in aqueous solution under UV light irradiation at room temperature and atmospheric pressure.