DEPOSITION AND ELECTROCHEMICAL CHARACTERIZATION OF TITANIUM OXIDE NANOSTRUCTURED THIN FILMS

The photo-activity for doped/undoped titania has been widely investigated in the last years and is actually exploited in many fields: photovoltaic energy productions1, hydrogen production by water splitting2, photocathodic protections of metals3, photo-degradation of bio-organics and inorganic pollutants4. The titania physical-chemical behavior is strongly related to the phase (anatase or rutile), the microstructure and stoichiometry and several preparation methodologies were fit out to control these parameters. Various parameters were carefully adjusted in order to tune the titania thin film phases, structure and morphology: power supply, total pressure, oxygen partial pressure, geometric configuration of sputtering process and substrate temperature control. Nanostructured thin films were deposited with selected allotropic structure at suitable rate without thermal post-treatment. The sample-holder motion allowed to obtain a different thickness distribution. Voltammetry and impedance spectroscopy analyses confirmed the photocatalytic activity under UV-VIS irradiation for undoped TiO2 films; under VIS irradiation, a low photo-activity was detected, higher for nitrogen-doped thin films.