Morphology modification of TiO2 nanotubes by controlling the starting material crystallite size for chemical synthesis

TiO2 nanotubes (NTs) were prepared by low-temperature chemical synthesis using anatase TiO2 particles with different crystallite sizes in a NaOH solution followed by water washing and HCl neutralization. The synthesized TiO2 NTs showed diverse morphologies depending on the starting materials. The crystallite size of TiO2 raw materials increased with an increase in annealing temperature, and larger TiO2 NTs, around 31 nm in diameter, were obtained from large raw powder with a crystallite size of 117 nm. X-ray diffraction and Raman spectroscopy revealed that the obtained TiO2 NT exhibited lower crystallinity; however, Raman vibration seems to be more likely than a rutile structure.