Synthesis and characterization of Zr⁴⁺, La³⁺ and Ce³⁺ doped mesoporous TiO₂: Evaluation of their photocatalytic activity

Sol-gel method was used to synthesize Zr⁴⁺, La³⁺ and Ce³⁺ doped mesoporous TiO₂ materials with different weight percentage (0.5, 1.0, 2.0 and 3.0wt%) using triblock copolymer as the structure directing template in ethanol/water medium. Characterization revealed the isomorphic substitution of Zr⁴⁺ ion into the lattice of TiO₂, and surface binding nature of La³⁺ and Ce³⁺ ions on mesoporous TiO₂. Microscopic examination confirmed the surface adsorption of foreign ion which could alter the particle morphology. The size of the particles was less than 20nm. Photocatalytic activity of metal ions doped mesoporous TiO₂ was evaluated using aqueous alachlor as a model pollutant. It was found that 1wt% Ce³⁺ doped mesoporous TiO₂ exhibited higher activity than pure and other metal ions doped mesoporous TiO₂. The change of oxidation state of Ce³⁺ is suggested to be the cause for enhanced photocatalytic activity.