Spatially confined corner defects induce chemical functionality of TiO ₂ nanorods

An atomic-resolution transmission electron microscopy (TEM) analysis of surface defect sites present at the tips of high-aspect-ratio ellipsoid nanoparticles of anatase titanium dioxide (TiO₂), was investigated. Modification of the nanorod tip surfaces with the enediol dopamine resulted in relaxation of the tip defect sites to their bulk-like octahedral symmetry. It was found that the convergence angle at the tip is specific to the aspect ratio of the rods whereby the tips of such particles converge at a more acute angle that have a pointed appearance. The chemical reactivity of the corner-defect-containing anisotropic rods is highly dependent on the presence of the under-coordinated titanium atoms. The results were identical to those obtained nanorods solely modified with dopamine and there was no extension or displacement of of the crystalline lattice after surface modification.