Effects of annealing on the composition, structure and photocatalytic properties of C-doped titania films deposited by reactive magnetron sputtering using CO2 as carbon source

Carbon-doped titania (C:TiO2) films were prepared by reactive magnetron sputtering using CO2 as a carbon source. The as-prepared films were annealed at different temperatures in vacuum condition. A TiO2 film using O2 gas was also prepared for comparisons with the C:TiO2. The structure and composition of the as-prepared, the TiO2 films and the annealed C:TiO2 films were analyzed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), while the surface morphology of the C:TiO2 films was measured by atomic force microscopy (AFM). Furthermore, photocatalytic properties of the films were evaluated by the degradation of methyl orange (MO). The results indicate that the photocatalytic property was improved when carbon was doped into TiO2 films, and the C:TiO2 films consist of anatase and TiO phases. The experimental results of the MO’s degradation confirm that the annealing process at various temperatures can modify the surface morphology of the films and the content of oxygen vacancies in the films. Consequently the variations in surface topography and oxygen vacancy potentially enhance the photocatalytic activity of TiO2 films