Synthesis of N-doped TiO₂ with different nitrogen concentrations by mild hydrothermal method

Nitrogen-doped nanocrystalline anatase TiO₂ powders with different nitrogen-doping concentrations were synthesized at 150 C and held for 2 h under an initial pressure of 3 MPa by the mild hydrothermal method with no postheat treatment. The X-ray photoelectron spectroscopy results confirmed that substitutional and interstitial nitrogen coexisted in the TiO₂ lattice and formed Ti-N and Ti-O-N linkages, respectively. The visible light absorption of nitrogen-doped TiO₂ in the wavelength 400 ~ 550 nm was greatly enhanced compared with that of un-doped TiO₂. Both optical absorption and photocatalytic efficiency were elevated with increased nitrogen-doping concentration.