Hierarchical SnO2@NiO core/shell nanoflake arrays as energy-saving electrochromic materials

Hierarchical SnO2@NiO core/shell nanoflake array on FTO-coated glass has been synthesized by a facile two-step solution method toward energy-saving electrochromism. Noticeably, the SnO2@NiO core/shell nanoflake array film shows a sustained memory effect, which is conducive to saving energy in commercial applications. The SnO2@NiO film exhibits an outstanding electrochromism, including large transmittance modulation (85.3%), fast switching speed (1.7 s and 2.4 s), high coloration efficiency (43.8 cm2 C−1), and excellent reversibility and cycling durability at 550 nm. The enhanced electrochromic performances can be attributed to the unique core/shell architecture, which provides large numbers of active sites for electrochemical reactions, fast ion and electron transfer channels and good strain accommodation ability.