Synthesis and photocatalytic activity assessing of the TiO₂ nanocomposites modified by some lanthanide ions and tin-derivative sandwich-type polyoxometalates

New nanocomposites containing sandwich-type polyoxometalate of [(PW₉O₃₄)₂(HOSn^IVOH)₃]¹²⁻ (P₂W₁₈Sn₃) loaded onto Ln-doped TiO₂ (Nd, Sm, Dy, Tb) nanoparticles were synthesized and their catalytic activities were assessed. The Ln–TiO₂ nanoparticles and Ln–TiO₂/P₂W₁₈Sn₃ nanocomposites were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction, field emission scanning electron microscope, energy dispersive analysis of X-rays spectra and diffuse reflectance spectra. The photocatalytic efficiency of the Ln–TiO₂ and Ln–TiO₂/P₂W₁₈Sn₃ were examined in the photodegradation of methyl orange and methylene blue solutions. It was revealed through different characterization techniques that the P₂W₁₈Sn₃ was successfully loaded on the lanthanide-doped anatase phase TiO₂ nanoparticles and the particles diameter were relatively 20–30 nanometers. It was revealed that doping by the lanthanide ions followed by loading of polyoxometalates improves the photocatalytic performance of TiO₂ effectively. The effects of operational parameters and the kinetics of photocatalytic degradation under UV light were discussed. The prepared nanocomposites were stable and could be easily separated from the reaction system.