Synthesis of Bi-doped TiO2 Nanotubes and Enhanced Photocatalytic Activity for Hydrogen Evolution from Glycerol Solution

Bi-doped TiO2 nanotubes with variable Bi/Ti ratios were synthesized by hydrothermal treatment in 10 mol center dot L1 NaOH (aq.) through using Bi-doped TiO2 particles derived from conventional sol-gel method as starting materials. The effects of Bi content on the morphology, textural properties, photo absorption and photocatalytic activity of TiO2 nanotubes were investigated. The scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) observations of the obtained samples revealed the formation of titanate nanotube structure doped with Bi, which exists as a higher oxidation state than Bi3+. Bi-doping TiO2 nanotubes exhibited an extension of light absorption into the visible region and improved photocatalytic activities for hydrogen production from a glycerol/water mixed solution as compared with pure TiO2 nanotubes. There was an optimal Bi-doped content for the photocatalytic hydrogen production, and high content of Bi would retard the phase transition of titanate to anatase and result in morphology change from nanotube to nanobelt, which in turn decreases the photocatlytic activity for hydrogen evolution.