Assembly of tungsten oxide nanobundles and their electrochromic properties

Lenticular W(18)O(49) nanobundles composed of ultra-thin nanowires with diameters of 5-10nm have been synthesized through a simple solvothermal method with hexachloride as precursor and mixed cyclohexanol and ethanol as solvent. Electrochromic films were prepared by assembling the W(18)O(49) nanobundle suspension onto tin-doped indium oxide (ITO) coated glass. Results showed that self-assembly of the W(18)O(49) nanobundles was strongly influenced by the solvents employed to disperse the nanobundles. The W(18)O(49) nanobundles coated films exhibited excellent electrochromic stability and reversibility. The W(18)O(49) nanobundle films also showed much higher charge-insertion density compared with the WO(3) nanorod film, which may be due to the ultrathin feature of single nanowires constituting the nanobundles, unique oxygen vacancies of monoclinic W(18)O(49), and the highly ordered assembly of the nanobundles. (C) 2011 Elsevier B. V. All rights reserved.