Electrochromic evaluation of airbrushed water-dispersible W18O49 nanorods obtained by microwave-assisted synthesis.

Motivated by the technological relevance of tungsten oxide nanostructures as valuable materials for highly efficient mesoporous electrodes suitable forenergy saving technology, electrochemical and electrochromic characteristics of greener processed nanostructured W18O49 based electrodes are discussed in this work. For the purpose, microwave-assisted water dispersible W18O49 nanorods have been synthesized and processedinto easily deposited nanostructured electrodes. Air-brushing technique has been adopted as cost-effective large-area scalable methodology to deposit the W18O49 nanorods onto conductive glass. This approach preserves the morphological and crystallographic habit of native nanorods and allows highly homogeneous transparent coating where good electronic coupling between nanowires is ensured by a mild thermal treatment (250°C, 30min). Morphological and structural characteristics of active material were investigated from the synthesis to entire nanocrystal deposition process by transmission and scanning electron microscopy (TEM, SEM) and X-ray diffraction (XRD). The as obtained nano-structured film exhibited good reversible electrochemical feature through several intercalation-deintercalation cycles. The electrochromic properties were evaluatedon the basis of spectroelectrochemical measurements and showed significant optical contrast in the near infrared region and high coloration efficiency at 550 nm.