Alcohol induced liquid-phase synthesis of rutile titania nanotubes

Pure rutile nanotubes were synthesized by a hydrothermal process in NaOH water–ethanol solution, starting from rutile-anatase TiO2 particles. The length of nanotubes is up to several micrometers and their diameter is uniform and not more than 20 nm. Although rutile phase is the high-temperature polymorph of anatase, the phase transformation from anatase of raw materials into rutile is realized at low-temperature (130 °C). The chelation of ethanol to the TiO6 octahedra, which are the basic building blocks of titania and separated by the alkaline dismantling of the TiO2 starting material, may play an important role for the phase transition. The nanotube evolution follows oriented assembly route from the seeds of the initially formed short nanotubes and with TiO6 octahedra as building blocks. The types of alcohol and the ratio of ethanol and H2O have a great impact on the morphology and structure of the final products. The rutile nanotubes present different opto-electronic properties from those of the raw TiO2.