N doping of TiO2 nanocrystal for efficient photodegradation of organic pollutants under ultraviolet and visible light irradiation

To decrease the band gap of TiO2 and enhance its photocatalytic performance, in this work, N-doped nanocrystalline TiO2 is synthesized successfully through a simple sol-gel synthesis process with dicyandiamide used as N source. The N-doped TiO2 photocatalysts have been characterized in detail by means of powder X-ray diffraction, Raman spectroscopy, infrared spectroscopy, UV-vis spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscope. The photocatalytic activities of N-doped TiO2 to different organic pollutants are significantly different. Using 2 × 10-5 mol/L methylene blue as the target pollutant, N-doped TiO2 can produced approximately 100% conversion within 40 min, the photocatalytic degradation ability of which is equal or superior to commercial or bare TiO2. The ameliorated photocatalytic activity of N-doped TiO2 photocatalysts is attributed to the appropriate crystallinity, good dispersibility, modified Zeta potential, and increased absorption.