Preparation of N-doped TiO2: characterization and photocatalytic performance under UV and visible light

Abstract

Nanocrystalline N-doped TiO₂ samples were prepared by using TiCl₄ or TiOSO₄ as precursors. The powders were characterized by X-ray diffraction, BET specific surface area measurements, scanning electron microscopy, diffuse reflectance spectroscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. The photocatalytic activity was tested using the photodegradation of 4-nitrophenol under UV and visible light.

Some samples were more active than commercial Degussa P25. A shift of the absorption edge to a lower energy and a stronger absorption in the visible light region were observed in the samples obtained from TiCl₄. Two absorption edges were observed in the samples derived from TiOSO₄ and calcined at 400 °C: the main edge due to TiO₂ and the second one due to the presence of a localised midgap band that induces the visible light activity.