Enhanced electrochromic performance of nanocomposite film based on Preyssler-type polyoxometalate and TiO2 nanowires

A nanocomposite film containing Preyssler-type polyoxometalate (POM) K12.5Na1.5[NaP5W30O110] (P5W30) and TiO2 nanowire arrays was fabricated by combining hydrothermal and Layer-by-Layer (LbL) self-assembly methods. Compared to individual TiO2 nanowire and P5W30 thin film, the composite films exhibits improved electrochromic properties of higher optical modulation (46.03% at 650 nm), faster switching times (7.03 s for coloration and 2.55 s for bleaching), outstanding coloration efficiency (163.4 cm(2)/C at 650 sun) and good cycling stability. Obviously, the enhancement of electrochromic performances can be attributed to the synergetic contribution from P5W30 and TiO2, which displays large real active area to support larger Li+ ion insertion and extraction sites. These advantages can make the nanocomposite film become a promising candidate for potential application in electrochromic devices.