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Effects of Zn²+ and Eu³+ Co-Doping on Photocatalytic Activity of TiO2

A series of Zn2+ and Eu3+ co-doped TiO2 catalysts were prepared by a modified sol-gel method. The prepared catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy(TEM) and ultraviolet-visible diffuse reflection spectroscopy(UV-vis DRS). Characteristic results clearly show that all of Zn2+ and Eu3+ co-doped TiO2 samples exclusively consist of primary anatase crystallites, the co-doping can retard the grain growth of TiO2 and decrease the aggregation of TiO2 nanoparticles. Zn2+ and Eu3+ co-doping increased the visible-light absorption ability of TiO2 catalysts and a red shift appeared when compared to pure TiO2. The photocatalytic activity of samples was evaluated by the photodegradation of methyl organge under natural light irradiation. Optimal doping amounts for Zn2+ and Eu3+ are 1.0% and 1.5% respectively, and two dopants of Zn2+ and Eu3+ in nanocrystalline TiO2 show a synergistic effect, which significantly increases the photocatalytic activity of TiO2. The photocatalytic mechanisms of Zn2+ and Eu3+ co-doped TiO2 catalysts were tentatively discussed.