Influence of Ytterbium Doping on the Visible Light Photocatalytic Activity of Mixed Phase TiO<sub>2</sub> Nanoparticles

The TiO 2 nanoparticles with different Yb doping amount were prepared by a facile sol-gel method. The samples were characterized by XRD, TEM, XPS, UV-Vis, and PL, etc. The influence of Yb-doping on structure and visible light photocatalytic activity of mixed phase TiO 2 was evaluated by photocatalytic degradation of methylene blue (MB) under the irradiation of fluorescent lamp. The results show that ytterbium appeared two kinds of Yb 3+ and Yb 2+ valence state on the surface of TiO 2 . Ytterbium doping can restrain the phase transfer from anatase to rutile, prevent the grain growth, and increase the surface hydroxyl content. Appropriate amount of Yb doping and the proportions of rutile and anatase mixed phase can effectively inhibit the recombination of photogenerated electron and hole, expand the wavelength range of absorption spectrum, and improve the photocatalytic performance of TiO 2 . Meanwhile, the photocatalytic activity of the Yb-TiO 2 samples was the best under the irradiation of fluorescent light when the sintered temperature T=500°C and n (Yb): n (Ti)=0.009, it was 95.2% within 6 h and significantly higher than 56.4% of pure TiO 2 under the same experimental conditions.