Efficient electrochromic materials based on TiO2@WO3 core/shell nanorod arrays

TiO2@WO3 core/shell nanorod arrays are prepared by the combination of hydrothermal and electrodeposition method. The array films show remarkable enhancement of the electrochromic properties. In particular, a significant optical modulation (57.2% at 750 nm, 70.3% at 1800 nm and 38.4% at 10 μm), fast switching speed (2.4 s and 1.6 s), high coloration efficiency (67.5 cm2 C−1 at 750 nm) and excellent cycling performance (65.1% after 10,000 cycles) are achieved for the core/shell nanorod arrays. The improved electrochromic properties are mainly attributed to the core/shell structure and the porous space among the nanorod array, which makes the ion diffusion become easier and it also gives larger surface area for charge-transfer reactions. The data present great promise for the TiO2@WO3 core/shell nanorod arrays as practical electrochromic materials.