Rational construction of MOF-derived Zn-Co-O/NiCo-LDH core/shell nanosheet arrays on nickel foam for high-performance supercapacitors

Abstract

A morphologically adjustable metal-organic framework (MOF) template and a unique hierarchical structure show improved electrochemical performance of electrode materials for supercapacitors. Herein, Zn/Co-MOF-derived zinc-cobalt oxide/nickel cobalt layered double hydroxides (Zn-Co-O/NiCo-LDH) hierarchical core/shell nanostructures on nickel foam (NF) were synthesized by simple methods and exhibited high specific capacitance. The results showed that both the reasonable morphology of the MOF-templated continuous nanosheet network and synergy between transition bimetallic oxides and transition bimetallic hydroxide played an important role in improving the electrochemical properties. Hence, the as-prepared Zn-Co-O/NiCo-LDH battery-type electrode exhibited excellent specific capacitance of 2275.2 F/g at 1 A/g and remarkable cycling stability of 82.4% capacitance retention after 5000 cycles. Moreover, the as-prepared Zn-Co-O/NiCo-LDH was used as the positive electrode to assemble a hybrid supercapacitor (HSC) device, which attained a distinguished energy density of 44.5 W h/kg at a power density of 800 W/kg and satisfactory stability (71.5% retention after 5000 cycles). It was concluded that MOF-templated core/shell heterostructures in electrode materials have broad prospects and great potential for energy storage.