Lanthanides doped TiO2 (Ln-TiO2; Ln= Pr, Nd, Sm, Eu, Tb) nanoparticles were synthesized by the sol–gel method. Sandwich type polyoxometalates of K10H2[(OCeIV)3(PW9O34)2].xH2O (PWCe) was loaded onto each of Ln-doped TiO2 nanoparticles by simple impregnation method. The Ln-TiO2 nanoparticles and Ln- TiO2/PWCe nanocomposites were characterized by Fourier transform infrared spectroscopy, high resolution scanning electron microscope, X-ray diffraction, energy dispersive spectra and diffuse reflectance spectra. Photocatalytic efficiency of Ln-TiO2 nanoparticles and Ln-TiO2/PWCe nanocomposites were examined in the photodegradation of methyl orange solution as a model. It was revealed through different characterization techniques that the PWCe sandwich type polyoxometalate was successfully loaded on the lanthanides-doped anatase phase TiO2 nanoparticles and the particles average sizes were diameter about 30 nm. It was revealed that however by doping the lanthanides ions improve performance of TiO2 but the best results obtained by loading of PWCe on Ln-TiO2. The results confirm a relationship between the electron affinity of Ln and photocatalytic activities of Ln-TiO2. The effects of operational parameters and the kinetics of photocatalytic degradation under UV light were discussed. The prepared nanocomposites were stable and can be easily separated from reaction system.
