Preparation and characterization of nitrogen and silver co-doped TiO2 nanocatalyst for visible light photocatalysis

Nitrogen and silver co-doped TiO2 photocatalytic material was prepared by improved sol-gel method. Physiochemical properties were characterized by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and ultraviolet-visible diffuse spectroscopy (UV-Vis). The results show that nitrogen doping is substituted into TiO2 lattice, but catalyst grain growth cannot be inhibited. Due to the addition of Ag element, catalyst grain growth is inhibited. Greatest band-gap narrowing occurs due to nitrogen and silver co-doping. The experiments of photogradation of phenol show that photocatalytic efficiency of catalysts prepared by the improved sol-gel method is significantly higher than that of catalysts prepared by the impregnation method. Under UV-visible irradiation for 120 min, the efficiency of nitrogen and silver co-doped TiO2 is 51. 3%, and the efficiency is 51. 7% under visible light irradiation for 360 min. Fortunately, visible photocatalytic activity is not realised at the cost of UV activity. Nitrogen and silver co-doping not only reduces band gap of TiO2, but also adjusts its absorption threshold to visible region. Simultaneously, oxygen vacancy concentration of catalysts increases and the response of catalysts to visible light significantly enhances, hence photocatalytic activity of nitrogen and silver co-doped TiO2 enhances.