Electrochromic properties of anodically grown mixed V2O5-TiO2 nanotubes

Mixed V2O5-TiO2 nanotube arrays were fabricated by self-organizing anodization of different Ti-V alloys. The mixed oxide nanotubes show switchable V-oxidation states and strong cathodic coloration. Already a low V content of approximate to 0.2 at.% significantly increases the electrochromic switching properties. Using a sample with 3 at.% V, very high electrochromic contrast can be established and a significantly lower switching onset voltage than for pure TiO2 nanotubes is observed. At high V contents, although charge storage is increased, the improvement of contrast is diminished due to the strong background color of the sample. (C) 2011 Elsevier B.V. All rights reserved.