Preparation and Photocatalysis Activity of Eu²⁺/Gd³⁺ codoped Nano-TiO₂ Multiplex Photocatalyst from Sol-Gel Process Catalyzed with Acid

A new nano-TiO_2 multiplex photocatalyst codoped with Eu~(2+)and Gd~(3+)was prepared by a modified acidic sol-gel process.TEM and XRD results demonstrate that as-produced samples are anatase structure,and the crystallite size has relationship only with total doped Eu~(2+)/Gd~(3+)content and the minimum size appeares at 1% doped content.UV-Vis absorption spectra show that Eu~(3+)/Gd~(3+) codoping can enhance the visible light response of the TiO_2.The photocatalyst activity of Eu~(2+)/Gd~(3+) codoped TiO_2 is evaluated by photodegradation of methyl orange in an aqueous solution under natural light irradiation,A synergetic effect is observed due to Eu~(2+)/Gd~(3+)codoping,and the optimal doping concentration for Gd~(3+)and Eu~(2+)are in the range from 0.1% to 1.0% and 0.5% to 1.5% respectively. The relationship and function between Eu~(2+),Gd~(3+)and TiO_2 are also discussed.