Synthesis of visible-light responsive nitrogen/carbon doped titania photocatalyst by mechanochemical doping

Nitrogen and/or carbon doped titania photocatalysts TiO2-x A (y) (A = N, C) were prepared by a novel mechanochemical method. The samples were prepared by a high-energy ball milling of P25 titania with different nitrogen/carbon sources such as hexamethylenetetramine, admantane or ammonium carbonate, followed by calcination in air at 400 degrees C. The high mechanical energy accelerated the phase transformation of anatase to rutile, while the existence of the chemical reagents tended to block the transformation. The prepared powders possessed two absorption edges around 400 and 540 nm and showed excellent photocatalytic ability for nitrogen monoxide oxidation under visible light irradiation. Under the irradiation of visible light of wavelength > 510 nm, 37% of nitrogen monoxide could be continuously removed by the carbon and nitrogen co-doped titania prepared by planetary ball milling of P25 titania-10% hexamethylenetetramine mixture followed by calcination in air at 400 degrees C. This mechanochemical technique might be widely useful for doping oxides with nonmetallic elements.