The reason for the improvement of photocatalytic activity is usually attributed to the decrease of the band gap, which is due to either mixing the nitrogen 2p states with O 2p states on the top of the valence band12 or the creation of a N-induced midgap level 20 as well as some impurity species (NOx,NHx). 21,22 Concerning the chemical states of N1s in the X-ray photoemission spectra (XPS), the assignment of XPS peak is still under debate with no consensus in the literature. In general, the peak of N1s in the XPS spectra mostly lies in the range of 396 404 eV, and there are different spectral features with different preparation methods and conditions. At present, N-doped TiO2 has been prepared by various methods such as mechanochemical reaction, sputtering, ion implantation, chemical vapor deposition, spray pyrolysis, sol gel, and oxidation of TiN. Most of the above methods need a higher temperature or complicated and expensive equipment; therefore, it is promising work to develop a simple and lower temperature method to extend the application of the nitrogen-doped TiO2 photocatalyst.