Titania nanofibers were grown on a titanium substrate using a hydrothermal reaction in an aqueous, concentrated sodium hydroxide solution. Post annealing in an ammonia atmosphere produced N-doped one-dimensional structures with a titanium dioxide structure and visible light absorption. The samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-Vis, Raman and X-ray photoelectron spectroscopy (XPS). The as-synthesized films showed a red shift and strong visible light absorbance between 400 and 700 nm, which is attributed to a doping effect. Photocatalytic activity in the aqueous phase under visible light irradiation led to the complete degradation of methylene blue within the first 3 h of the reaction. A visible-light-driven superhydrophilic effect was also observed.

Keywords: Nitrogen doping, Titanium dioxide, Photocatalysis, Visible light, Nanofibers, Hydrothermal reaction