High-Properties electrochromic device based on TiO2@Graphene/Prussian blue Core-Shell nanostructures

Herein, the successful preparation of a high-performance electrochromic device (ECD) with the TNRA@G/PB core–shell nanostructure as the electrode has been described. The core–shell nanostructure was formed by wrapping graphene (G) and growing Prussian blue (PB) on the TiO 2 nanorod array (TNRA) through the two-step hydrothermal and spin coating method. The existence state of elemental iron (Fe) and the evolution of the PB growth layer were studied by X-ray photoelectron spectroscopy (XPS) depth profiles. In addition, a model of K + diffusion and electron transport in the ECDs was proposed to explain the mechanism of the enhanced electrochromic property of the TNRA@G/PB core–shell nanostructures. The TNRA as a support template is conducive to electrolyte penetration and rapid ion replenishment to active sites. At the same time, the porous structure can alleviate the volume expansion during the electrical cycle which will increase the cycle stability of ECDs. G acts as a bridge between the conductive and active layer and can reduce the loss of electrons between interfaces in the transport process. It provides a fast transport channel for electrons and promotes the rapid response of electrochromism. Compared with ECDs based on the traditional PB film, TNRA@G/PB core–shell nanostructures achieve a higher optical modulation range (56.1%) and a shorter switching time (t c /t b  = 1.0/2.8 s). In particular, the coloration efficiency (CE) has been significantly increased to 129.1 cm 2 /C at a wavelength of 700 nm, which shows a promising application in high-performance ECDs.