Carbon nanotubes-assisted polyoxometalate nanocomposite film with enhanced electrochromic performance

A nanocomposite film containing polyoxometalates (POMs) cluster K6P2W18O62·14H2O (P2W18), carbon nanotubes (CNTs) and chitosan (CS) was fabricated by layer-by-layer (LbL) methods. The composite material displays enhanced electrochromic performance, with the optical contrast of 20.3% and coloration efficiency of 91.5 cm2 C−1 at 620 nm. Furthermore, the composite material displays the increased thickness and surface roughness by incorporation of CNTs into the P2W18 film. Obviously, the presence of CNTs has the strong influence on the multilayer structure, leading to high optical contrast and coloration efficiency. The results demonstrate the essential role of CNTs in enhancing functionality on POMs for applications of electrochromic devices.

Graphical abstractThe optical contrast achieves 20.3% by incorporation of CNTs into the P2W18 films, showing the CNTs could obviously improve the electrochromic performances of POMs-based films.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The effect of carbon nanotubes on the electrochromic performances of polyoxometalate-based films was investigated in detail. ► The electrochromic performances of the composite material is obviously improved by incorporation of carbon nanotubes into the P2W18 films ► The optical contrast and coloration efficiency achieve 20.3% and 91.5 cm2 C−1, respectively. ► Electrochemically induced oxidation–reduction reaction is related with electrochromism.