One-step synthesis of nanocrystalline N-doped TiO2 powders and their photocatalytic activity under visible light irradiation

Nanocrystalline N-doped TiO2 powders were successfully prepared by hydrothermal reaction for 2 h at low temperature (120 A degrees C) and at an applied pressure of 3 MPa. The grain size of the powders (calculated by use of Scherrer's method) ranged from 8.2 to 10.2 nm. The BET specific surface area ranged from 151.0 to 220.0 m(2)/g. A significant shift of the light absorption edge toward the visible light zone was observed in the UV-visible spectra. XPS results showed that nitrogen atoms were incorporated into the TiO2 lattice. The photocatalytic activity of the synthesized N-doped TiO2 powders was evaluated by measurement of photodegradation of methylene blue (MB) in aqueous solution under visible light irradiation. The amount of MB degraded increased with increasing illumination intensity.