Vanadium oxide nanorods (VONRs) and vanadium oxide nanotubes (VONTs) were fabricated by hydrothermal method with the induction of hydroxyl and carboxyl functionalized carbon nanotubes (CNTs). The functionalized CNTs not only facilitate the dispersion of CNTs but also serve as centers for polymerization in the hydrothermal reaction. The formation of (VONRs) and (VONTs) was observed by field emission scanning electron microscopy, transmission electron microscopy, x-ray powder diffraction and Fourier transform infrared spectroscopy tests. Self-assembling nanotubes and nanorods were formed together with the layered structures, but they followed different formation mechanisms. The “Rolling” and “Attaching-Oriented Attachment Growth” mechanisms are proposed to describe the formation of VONRs and VONTs, respectively.

Mo doped vanadium oxide nanotubes (VONT) were formed via a rheological phase reaction followed by self-assembling process and were heated at 400 □ in an inert atmosphere. The nanotubes were characterized by SEM, HRTEM, XRD, FTIR, electrochemical investigation, etc. In contrast to the undoped VONTs, the interlayer distance between oxide layers in the (V0.99Mo0.01)xONTs increases owing to replacement of some V in nanotubes by Mo with a larger ionic radius, resulting in a shorten diffusion length of Li ions and an improved electrochemical performance. The electrochemical performance of (V0.99Mo0.01)xONTs is further enhanced by removing the residual organic template by heating in an inert atmosphere.

Vanadium dioxide nanorods (B phase) have been synthesized, for the first time, using cetyltrimethylammonium bromide (CTAB) as structure-directing template in hydrothermal condition. Morphology and structure of the sample were characterized by XRD, SEM, HRTEM, XPS, TG-DTA and redox titration. The results show that the products are VO2 (B) nanorods and they are 1∼2 μm in length. HRTEM micrographs reveal that they indeed form bundles of agglomerated smaller filaments with diameters ranging from 20 to 40 nm. This filament-like shape in the nanoscale dimension leads to the exposure of a large fraction of the atoms to the surface. Thus, these materials are promising candidates for the development of new functionalized materials. TG investigation shows that there are a weight loss of 2.21 % between 250∼400 °C corresponding to removal of the organic residuals and a weight gain at about 430 °C corresponding to oxidation of vanadium with low oxidation state. The simplicity of hydrothermal process, cheapness, and availability of raw materials are advantages favoring the scaling-up of nanorods.