Characterization and photocatalytic activity of N –doped TiO2 prepared by thermal decomposition of Ti–melamine complex

Abstract

Nitrogen doped spherical TiO2 has been prepared by thermal decomposition of Ti-Melamine complex in air atmosphere. A clear shift in the onset light absorption from UV region (<400) to visible region (>520 nm) has been observed for the N-doped samples. It has been deduced from the optical absorption spectra that the higher calcination temperature results in the decreases of amount of N-doping. The XRD results revealed the phase transition of TiO2 from anatase to rutile crystalline phase, starting at calcination temperature ≥ 600 0 C. The electron microscopic images reveal the formation of spherical and flakes of TiO2 nanocrystals (25 nm). The chemical nature of N in the NTiO2 has been evolved through X-ray photoelectron spectroscopy. The presence of different types of N species have been observed corresponding to different oxidation state and the presence of Ti-N and O-Ti-N environment has been confirmed from the observed binding energy values. Photocatalytic decomposition of methylene blue has been carried out both in the visible region and UV+Visible region. N-TiO2 showed higher activity compared to the undoped commercial TiO2 (Degussa P25) photocatalyst in the visible region.