Large-scale growth of single-crystalline TiO_{2 nanowires and their visible-light photocatalytic activity

Single–crystalline TiO2 nanowires were successfully grown by oxidation of as–sputtered Ti films with ethanol. X–ray diffractometer (XRD) and high resolution transmission electron microscopy (HRTEM) studies revealed that the nanowires had a single–crystalline structure and grew along the [110] axis. The formation of the TiO2 thin film was found to play an important role in the nanowire growth due to the ability to reduce the diffusion rates of Ti atoms from Ti films for the limited nucleation by thermally activated. The growth of TiO2 nanowires was determined by the reaction of ethanol with Ti diffusion which was supplied from the Ti films. The TiO2 nanowires showed an efficient visible–light photocatalytic activity. Moreover, after thermal annealing, both UV and visible–light photocatalytic activities of TiO2 nanowires were enhanced significantly due to the increase in the surface defects on the nanowires.