Photocatalytic activities of Pd-loaded mesoporous TiO2 thin films

In the present study, transparent nanocrystalline Pd–TiO2 films were prepared by a sol–gel spin coating technique. By introducing non-ionic surfactant Triton X-100 into the sol, transparent mesoporous Pd–TiO2 films were also prepared after calcination at 500 °C. To reveal the structural and morphological differences, the as-prepared TiO2 and Pd–TiO2 films were characterized by scanning electron microscope with energy dispersive spectrometer, thermal gravimetric analysis, X-ray diffraction and UV–vis spectrophotometer. In addition, the photocatalytic activities of these films were investigated by degrading methylene blue under UV and visible light irradiation. Sol–gel TiO2 film, processed without surfactant, exhibited a pore-free smooth surface. Mesoporous TiO2 and Pd–TiO2 films with pore sizes ranging from 4 to 20 nm were obtained when surfactant was introduced and removed after calcination. In this study, the mesoporous Pd–TiO2 film with molar ratio of Pd/Ti = 0.05 exhibited the best photocatalytic activity while specifically maintained good transparency.