Preparation and characterization of graphene-based vanadium oxide composite semiconducting films with horizontally aligned nanowire arrays

Abstract

Highly oriented crystalline hybrid thin films primarily consisting of Magneli-phase VO2 and conductive graphene nanoplatelets are fabricated by a sol-gel process via dipping pyrolysis. A combination of chemical, microstructural, and electrical analyses reveals that graphene oxide (GO)-templated vanadium oxide (VOx) nanocomposite films exhibit a vertically stacked multi-lamellar nanostructure consisting of horizontally aligned vanadium oxide nanowire (VNW) arrays along the (hk0) set of planes on a GO template, with an average crystallite size of 41.4 angstrom and a crystallographic tensile strain of 0.83%. In addition, GO-derived VOx composite semiconducting films, which have an sp(3)/sp(2) bonding ratio of 0.862, display thermally induced electrical switching properties in the temperature range of -20 degrees C to 140 degrees C, with a transition temperature of approximately 65 degrees C. We ascribe these results to the use of GO sheets, which serve as a morphological growth template aswell as an electrochemically tunable platform for enhancing the charge-carrier mobility. Moreover, the experimental studies demonstrate that graphene-based Magneli-phase VOx composite semiconducting films can be used in advanced thermo-sensitive smart sensing/switching applications because of their outstanding thermo-electrodynamic properties and high surface charge density induced by the planar-type VNWs. (C) 2016 Elsevier B.V. All rights reserved.