TiO2 nanotubes; Raman spectra; template synthesis; alumina template.
TiO2 nanotubes have been synthesized by sol–gel template method using alumina membrane. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, UV absorption spectrum and X-ray diffraction techniques have been used to investigate the structure, morphology and optical properties of TiO2 nanotubes. SEM image showed that TiO2 nanotubes obtained were ordered and uniform. The diameter and length of the nanotubes were decided by the pore size and thickness of alumina template. Raman and XRD measurements confirmed the crystallinity and anatase phase of the TiO2 nanotubes. The optical absorption measurement of TiO2 nanotubes exhibits a blue shift with respect to that of the bulk TiO2 owing to the quantum size effect.