One-step preparation of C-doped TiO2 nanotubes with enhanced photocatalytic activity by a water-assisted method

Abstract

The crystallization of amorphous TiO₂ nanotubes, which were prepared by anodic oxidation, was carried out by a water-assisted method at low temperatures. The crystalline phase and the morphology of TiO₂ nanotubes were observed by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM), respectively, and the photocatalytic activity was characterized by the degradation of methylene blue (MB). Results show that TiO₂ nanotubes crystallized by a water-assisted method at 50 °C for 4 h exhibited high crystallinity, a preferable nanotube structure and therefore, high photocatalytic activity. Sucrose was added to the aqueous solution as a carbon source for preparing C-doped TiO₂ nanotubes. X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS) were used to observe the chemical state of C-doped TiO₂ nanotubes. After C-doping, the crystalline phase and morphology of TiO₂ nanotubes hardly changed but the bandgap of TiO₂ was narrowed, which endowed TiO₂ nanotubes with wide-range light absorption, significantly enhancing the photocatalytic activity. This one-step method at a low temperature of 50 °C provides a new pathway for preparing C-doped TiO₂ nanotube photocatalysts with enhanced photocatalytic activity.