Construction of TiO₂@C@Prussian Blue core-shell nanorod arrays for enhanced electrochromic switching speed and cycle stability

In this study, a novel TiO₂@C@Prussian Blue core-shell nanorod arrays film was constructed through two-step hydrothermal and electrodeposition methods. Such a designed structure could increase the specific surface area, reactive site, and conductivity of Prussian Blue (PB) and reduce the diffusion distance of ions due to the nano-architecture arrays of TiO₂ and the high conductivity of the carbon layer, thus leading to the remarkably improved storage capacity and reaction speed of ions during the electrochromic (EC) process of PB. Moreover, porous morphology and strong adhesion on the FTO substrate of the TiO₂ nanorod arrays could alleviate the lattice stress and volume expansion and enhance the binding force, thus improving the cycle stability of EC. Given these benefits, the TiO₂@C@PB films display a large optical modulation range (67%), fast switching speed (t_c/t_b = 1.25 s/2.71 s), and high coloration efficiency (129.4 cm²/C). In particular, the EC cycle stability is remarkably improved (96.3% after 5000 cycles), implying a promising application in high-performance EC devices (ECDs).