[Fabrication and photocatalytic activity of Pt-inserted titania nanotubes]

Titania nanotubes (TNTs) were synthesized by hydrothermal treatment of rutile-phase TiO2 nanoparticals in NaOH solution at 110 degrees C for 24 hours. After drying in aceton for 36 h, the TNTs were under vacuum drying for 24 h at room temperature. The Pt-inserted titania nanotubes (Pt/TNTs) were obtained by filling H2 PtCl6 ethanol solution into the TNTs after vacuum drying. The characterizations of the as-synthesized samples were confirmed by TEM, XRD, and UV-Vis. The photocatalytic activity of the Pt/TNTs was investigated by photo-induced decomposition of methyl orange(MO)under the main 365 nm UV-light. In order to comparison, the photocatalytic activity of both the rutile-phase TiO2 nanoparticles and pure TNTs were also investigated at the same time under the same experimental conditions. The TEM images show that the TNTs are hollow, a few hundred nanometers long, and the inner/outer diameter is about 6/10 nm. The crystal structure of TNTs is H2Ti2O5 x H2O with a little Na. Both the shape and the crystalline of the TNTs are not changed after the modification. The oval or round Pt0 nanoparticals, about 3 nm in diameter, are found only in the nanotubes. Pt/TNTs exhibit enhanced absorption at the visible range in the UV-Vis spectra and its start absorption band edge(lambda0 approximately 457 nm)is obviously redshifted compared to the rutile-phase TiO2 nanoparticals and pure TNTs. The Pt nanoparticles are found to significantly enhance the photocatalytic activity of TNTs. Pt/TNTs are demonstrated to be highly efficient for the UV-light induced photocatalytic decomposition of MO compared to both the rutile-phase TiO2 nanoparticals and pure TNTs. After irradiation for 60 min, the photocatalysis decomposition rate of MO in rutile-phase TiO2 nanoparticals, TNTs and Pt/TNTs are 46.8%, 57.2% and 84.6% respectively.