Rational design of nickel oxide/cobalt hydroxide heterostructure with configuration towards high-performance electrochromic-supercapacitor

[Display omitted] •A novel porous NiO/Co(OH)2 heterostructure was fabricated by a stepwise method.•The strategy was proposed to obtain fast switching and sustainable memory effect.•The effect of heterojunction on the EC performance enhancement was investigated.•Improved charge storage behavior was observed for the unique architecture. Transition metal oxides are envisioned as promising electrochromic and energy-saving materials, and the benign presence of hydroxides can further improve the performance. However, rational design and directional synthesis of well-defined porous hierarchical heterostructure for high-performance electrochromic-supercapacitor electrode is highly desired yet challenging. Herein, NiO/Co(OH)2 heterogenous nanoflake arrays have been successfully prepared on FTO-coated glass substrate through a facile but powerful stepwise method. Benefited from this unique architecture, the heterostructure exhibited improved optical modulation (72.15 % at 550 nm), fast ions transfer kinetics (tb/tc = 1.8/3.4 s), high coloration efficiency (49.80 cm2·C-1), sustained memory effect (only 9.57 % attenuation after aging for 24 h) as well as areal specific capacitance of 24.63 mF·cm−2 at the discharging current density of 0.1 mA·cm−2. The relationship between the excellent performance and the determining parameters involved favorable porous structural with the constructed heterojunction which boosted the charge transportation has been unveiled. Our work developed here can offer an enlightenment for the preparation of versatile heterogeneous structures, which can bring new design opportunity for energy-storage applications in the future.