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.