Preparation of visible light responsive N doped TiO2 via a reduction–nitridation procedure by nonthermal plasma treatment

A visible light responsive N-doped TiO2 was prepared via a reduction–nitridation procedure by nonthermal plasma treatment. X-ray diffraction, N2 adsorption, UV–vis spectroscopy, photoluminescence, and X-ray photoelectron spectroscopy were used to characterize the prepared TiO2 samples. The plasma treatment did not change the phase composition and particle sizes of TiO2 samples, but extended its absorption edges to the visible light region. The photocatalytic activities were tested in the degradation of an aqueous solution of a reactive dyestuff, methylene blue, under visible light. The photocatalytic activities of TiO2 prepared by reduction–nitridation procedure were much higher than that of samples prepared by simple nitridation treatment. The enhanced activity was ascribed to the substitutional N-doping and appropriate concentration of oxygen vacancies. TOHN10 prepared by reduction–nitridation procedure exhibited excellent photocatalytic stability. A possible mechanism for the photocatalysis was proposed.