*Article* **The Preparation of N-Doped Titanium Dioxide Films and Their Degradation of Organic Pollutants**

**Yanyan Dou <sup>1</sup> , Yixuan Chang <sup>1</sup> , Xuejun Duan 1,\*, Leilei Fan <sup>2</sup> , Bo Yang 3,\* and Jingjing Lv <sup>1</sup>**


**Abstract:** N-doped TiO<sup>2</sup> films supported by glass slides showed superior photocatalytic efficiency compared with naked TiO<sup>2</sup> powder due to them being easier to separate and especially being responsive to visible light. The films in this study were prepared via the sol–gel method using TBOT hydrolyzed in an ethanol solution and the nitrogen was provided by cabamide. The N-doped TiO<sup>2</sup> coatings were prepared via a dip-coating method on glass substrates (30 × 30 × 2 mm) and then annealed in air at 490 ◦C for 3 h. The samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-vis. The doping rate of N ranged from 0.1 to 0.9 (molar ratio), which caused redshifts to a longer wavelength as seen in the UV-vis analysis. The photocatalytic activity was investigated in terms of the degradation of phenol under both UV light and visible light over 4 h. Under UV light, the degradation rate of phenol ranged from 86% to 94% for all the samples because of the sufficient photon energy from the UV light. Meanwhile, under visible light, a peak appeared at the N-doping rate of 0.5, which had a degrading efficiency that reached 79.2%, and the lowest degradation rate was 32.9%. The SEM, XRD and UV-vis experimental results were consistent with each other.

**Keywords:** photocatalysis; N-doped films; visible light; titanium dioxide
