Abstract
Hydrous vanadium oxides (denoted hereafter as VO x yH 2 O) were prepared by anodic deposition from an aqueous solution containing VOSO 4 and H 2 O 2 . X-ray photoelectron spectroscopic analyses demonstrated that the valence of vanadium in the deposits was mixed pentavalent and tetravalent. Growth of vanadium oxide nanowires to unique sea-urchin-like structure from the as-deposited oxides can be induced by postdeposition annealing in air at 400°C with time 4 h. The success in growing one-dimensional (1D) vanadium oxide nanowires strongly depends on the deposition variables such as the V 5+ /V 4+ ratio (adjusted by H 2 O 2 addition) in the VOSO 4 solution and the applied current density during anodic deposition. From the transmission electron microscopic and selected area electron diffraction analyses, nanowires show single-crystalline structures of V 2 O 5 , α -V 2 O 5 , and V 6 O13. This thermal-induced growth of 1D vanadium oxide nanowires is attributable to the extrusion of V 2 O 5 , α -V 2 O 5 , and V 6 O13 single crystals originating from the thermal expansion of VO x yH 2 O. © 2009 The Electrochemical Society.