A Novel Approach to Vanadium Oxide Nanotubes by Oxidation of V4+ species

Mixed-valence vanadium oxide nanotubes (VOx-NTs) were synthesized by a new route starting from the oxidation of a vanadyl (IV) acetate precursor. The formation of a layered structure- which is necessary for eventually obtaining nanotubes was confirmed. The partial oxidation of this layered composite by hydrothermal treatment produces VOx-NTs, which are identical to those obtained from V5+ precursors. The influence of the structure-directing amine compound was studied and it was found that the optimal V/amine ratio required to obtain good quality nanotubes is 0.5. Moreover, it was found that in order to get a complete folding of the laminar precursor into nanotubes a V4+/V5+ ratio of about 1.0 should be attained.