Preparation of a visibly photo-active TiO2-xNx by planetary grinding of TiO2 with NH3 for an application in photocatalytic product design and manufacture

Nitrogen-doped TiO2 (N-TiO2), which shows a good photocatalytic activity to visible light irradiation, was successfully prepared by grinding TiO2 with gaseous NH3. Nitrogen doping into TiO2 induced narrowing of the band-gap, which resulted in more sensitive photo-activity to visible light irradiation. The procedure of nitrogen-doping was verified by X-ray photoelectron spectroscopy (XPS), NOx decomposition activity, FT-IR spectrometry, UV-vis analysis and hydrogen detection results. The nitrogen doping was performed as follows, adsorption of gaseous NH3 on TiO2 surfaces and reaction with the activated surfaces of TiO2. New Ti-N bonds were generated before the breakage of N-H bonds of NH3 adsorbed on TiO2. Finally, the prolonged grinding operation broke N-H bonds with the generation of H-2, which resulted in the successful preparation of N doped TiO2.