Structural Feature and Catalytic Performance of Cu Species Distributed over TiO2 Nanotubes

The fabrication and characterization of novel carbon doped TiO2 nanotubes, nanowires and nanorods with high visible light photocatalytic activity

Novel carbon doped TiO(2) nanotubes, nanowires and nanorods were fabricated by utilizing the nanoconfinement of hollow titanate nanotubes (TNTs). The fabrication process included adsorption of ethanol molecules in the inner space of TNTs and thermal treatment of the complex in inert N(2) atmosphere. The structural morphology of carbon doped TiO(2) nanostructures can be tuned using the calcination temperature. X-ray diffraction, Raman and Brunauer-Emmett-Teller studies proved that the doped carbon promoted the crystallization and phase transition by acting as nucleation seeds. X-ray photoelectron spectroscopy (XPS) showed that O-Ti-C and Ti-O-C bonds were formed in the nanostructures. Additional electronic states from the XPS valence band due to carbon doping were observed. This evidence indicated the electronic origin of the band gap narrowing and visible light absorption. The differences in chemical and electronic states between the surface and bulk of as-prepared samples confirmed that carbon was doped into the lattice of TiO(2) nanostructure through an inner doping process. The as-prepared catalysts exhibited enhanced photocatalytic activity for degradation of toluene in gas phase under both visible and simulated solar light irradiation compared with that of commercial Degussa P25. This novel fabrication approach can valuably contribute to designing nanostructured photocatalytic materials and modifying various nanotube materials.

Characterization and photocatalytic activities of C, N and S co-doped TiO(2) with 1D nanostructure prepared by the nano-confinement effect

A novel method was developed for preparing high specific surface area (156.2 m(2) g(-1)) one-dimensional TiO(2) nanostructures co-doped with C, N and S by the nano-confinement effect. A nonmetal doping source (thiourea) was first intercalated into the inner space of H-titanate nanotubes prepared by the hydrothermal method, and then calcined at 450 °C for 2 h in air. The as-prepared C, N and S co-doped TiO(2) nanowires exhibited high visible light and enhanced UV-vis activities in photocatalytic degradation of toluene in the gas phase. The samples were characterized by x-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, fast Fourier transform analysis, x-ray photoelectron spectroscopy, UV-vis diffuse reflectance spectra and photoluminescence. The results indicated that the anatase nanowires grew along the [101] direction. Doping TiO(2) nanowires with C, N and S could not only broaden the light adsorption spectra into the visible region (400-600 nm), but also inhibit the recombination of photo-induced carriers. A mechanism is proposed to elucidate the nano-confinement effect of H-titanate nanotubes in the formation of C, N and S co-doping. Based on this mechanism, the effect of C, N and S co-doping on the band structure of TiO(2) nanowires is also discussed.