Direct observation of TiO₆ octahedron forming titanate nanotube by advanced transmission electron microscopy

The nanostructure of titanate nanotubes known as a one-dimensional catalytic/electric subject is combinatorially characterized using x-ray diffraction (XRD), micro-Raman, photoluminescence (PL) and advanced electron microscopy. The micro-Raman and PL spectra prove the successful synthesis of TiO₆ octahedron units in macroscopic scale. Cryo-high-angle annular dark-field (HAADF)-STEM and aberration-corrected (AC) TEM visualize in real-space the TiO₆ octahedron unit formed as a TiO₂-based tubular structure prepared by the alkaline hydrothermal methods. The chirality and scrolling-up mechanism of the TiO₆ octahedron nanosheets in relation to an asymmetrical chemical environment and mechanical tensions are discussed.