Preparation and photocatalytic performance of titania nanotubes loaded with Ag nanoparticles

Titania nanotubes (TNTs) were synthesized by hydrothermal treatment of rutile-phase TiO₂ nanoparticles in 10 mol· L^-1 NaOH solution at 110 °C for 24 h. The Ag loaded titania nanotubes (Ag/TNTs) were obtained by chemical deposition method with the TNTs suspending in the AgNO₃ solution (pH=8) at 50 °C. The characterizations of the as-synthesized samples were performed by TEM, EDS, XRD, XPS, and UV-Vis spectra. The photocatalytic performance of the Ag/TNTs was investigated by UV-light induced photocatalytic decomposition of methyl orange(MO). The results showed that the inner/outer diameters of TNTs were about 6/10 nm and the length was several hundred nanometers. Both the shape and the crystalline of the nanotubes were not changed after the modification. The zero oxidation state Ag quantum dots, about 4 nm in diameter, were well dispersed on the external surface of the nanotubes. Ag/TNTs exhibited enhanced absorption at the visible range in the UV-Vis spectra. The Ag nanoparticles were found to significantly enhance the photocatalytic activity of TiO₂ nanotubes, and the catalyst system was demonstrated to be highly efficient for the UV-light induced photocatalytic decomposition of MO compared to both rutile-phase TiO₂ nanoparticles and pure TNTs. After irradiation for 60 min, the decomposition rates of MO solution in rutile-phase TiO₂ nanoparticles, TNTs, and Ag/TNTs system were 46.8%, 57.2%, and 92.2%, respectively.