Photocatalytic degradation of methylene blue with TiO<inf>2</inf> by doping with rare earth ions (Y<sup>3+</sup>, La<sup>3+</sup>and Nd<sup>3+</sup>)

Abstract

Rare earth ions (Y3+,La3+,Nd3+) doped TiO 2 catalysts were prepared by the sol-gel method, and characterized by X-ray diffraction (XRD) and UV-vis diffuse reflectance spectroscopy (DRS). The photocatalytic activities of doped TiO 2 were evaluated with methylene blue degradation under UV light. The anatase to rutile phase transformation of doped TiO 2 was significantly inhibited by rare earth ions doping, and the inhibitory effect was related to ion radius with a sequence of La3+> Y3+> Nd3+. The doped rare earth ions were in form of rare earth oxides, which adsorbed on TiO 2 surface to efficiently separate charge carriers. Rare earth ion doping in TiO 2 can extend light absorption properties to the visible region, which indicates the reduced band gap position of doped TiO 2 . The content of doped rare earth ions was an important factor affecting photocatalytic activity. The optimum amount of rare earth doping is 0.1∼0.15wt%, at which the photo-reactivities of doped TiO 2 were about 20% higher than that of pure TiO 2 .