Ultrasonic synthesis and photocatalytic performance of metal-ions doped TiO2 catalysts under solar light irradiation

Abstract Eight metal-ions doped TiO 2 (M-TiO 2 ) were successfully synthesized by an ultrasonic method, including Fe, Co, Ce, Cr, Mn, Mg, Ni and Ag ions. Among them, the 1% Mg–TiO 2 shows the highest photocatalytic efficiency under solar light, which was determined by degrading rhodamine B (RhB) molecules in an aqueous solution. The synthesized M-TiO 2 samples were characterized by XRD, BET Surface area, TEM, XPS and diffuse reflectance spectrum. Effects of synthesis conditions and characterized properties on photocatalytic efficiency of the M-TiO 2 were investigated comprehensively. A positive correlation between specific surface area and photocatalytic efficiency of the M-TiO 2 was found across different synthesis conditions. However, no clear correlation with photocatalytic efficiency was observed for crystal structure and radii of doping ions of the M-TiO 2 . XPS study indicates the change of oxidation states of Mn ions in Mn–TiO 2 during synthesis procedure from the initial Mn 2+ to a mixture of Mn 3+ and Mn 4+ ions. Dye sensitization mechanism was observed during the photocatalytic procedure of the Mg–TiO 2 , which enhanced the degradation efficiency of the Mg–TiO 2 under solar light. Finally, no obvious loss of photocatalytic activity was observed for the Mg–TiO 2 after five cycles of RhB degradation.