Preparation and characterization of nitrogen-doped titanium dioxide

To extend the absorption range of titanium dioxide into the visible-light region, the nitrogen incorporation process is investigated. This work presents a simple procedure for preparing nitrogen doped titanium dioxide nanocrystal (TiO _xN _y) by calcinating the mixture of Degussa P-25 (DP-25) TiO ₂ and NH ₄Cl at temperatures between 350 and 500 °C under airtight condition. Analysis of X-ray photoelectron spectroscopy indicated the molecular state nitrogen was incorporated into TiO ₂ lattice leading to the observable shift of the absorption edge to longer wavelength region with higher absorption intensity. These TiO _x N _y samples exhibit photocatalytic activity for methylene blue decomposition in aqueous solution under visible light irradiation. The correlation between the photocatalytic activity of TiO _xN _y and nitrogen content, rutile phase composition, and surface area was investigated and discussed.