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

Novel carbon doped TiO2 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 TiO2 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 TiO2 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.