Structural Studies of V₂O₅ Nanowires by Ultrahigh Vacuum-Scanning Tunneling Microscope and Atomic Force Microscope

We have investigated the structures and electronic properties of vanadium pentoxide (V₂O₅) nanowires synthesized by a sol–gel process. The time-dependent evolution of the V₂O₅ nanowires at different temperatures was systematically studied by atomic force microscopy. The structural dimension and the current–voltage (I–V) characteristics were measured by scanning tunneling microscopy/spectroscopy. V₂O₅ nanowires with a cross section of 10×1.5 nm², whose length varied with the duration time in sol, were synthesized. The V₂O₅ nanowires adsorbed on a self-assembled monolayer of aminothiophenol (ATP) on a Au(111)/mica substrate showed semiconducting I–V characteristics. The height of the V₂O₅ nanowires decreased from 1.5 to 0.8 nm with prolonged annealing at temperatures above 100 °C, implying the existence of a water interlayer in the V₂O₅ double-layer structure.