Oriented Crystal Growth Model Explains the Formation of Titania Nanotubes

We discuss the formation mechanism of titania nanotubes synthesized by the hydrothermal method. On the basis of a comprehensive analysis of TEM, HRTEM, FT-Raman, and N2 adsorption data, we point out some major shortcomings of the currently accepted trititanate sheet rollup mechanism. We suggest that a novel formation mechanism, oriented nanotube crystal growth from nanoloop seeds, can explain the experimental findings better than the ones proposed so far.