Vanadium-oxide nanotubes: Synthesis and template-related electrochemical properties

The electrochemistry of mixed-valent-containing vanadium-oxide nanotubes (VOx-NTs) is first reported. Using dodecylamine and hexadecylamine as templates, two kinds of VOx-NTs were synthesized and characterized. Both VOx-NTs contain V2O3, VO2 and V2O5 species. Dodecylamine-templated VOx-NTs (C12-VOx-NTs) are much more stable than hexadecylamine-templated VOx-NTs (C16-VOx-NTs). C12-VOx-NTs demonstrate stable redox behavior at ∼−0.2 V, which is arising from the electrochemical transfer between V(III) and V(IV), whereas C16-VOx-NTs exhibit unstable and weak redox peaks. In both cases, the reduction reaction of V(V)–V(IV) is never observed. The oxidation peak for V(IV) appeared only after a relatively long time immersion, suggesting that some small molecules such as water intercalate into the layered nanostructures before the electrochemical reaction. The difference may be an origin of the different template-induced the electroactivity of vanadium-oxide species in the nanotube-microenvironment.