Controllable Transformation of Metal–Organic Framework Nanosheets into Oxygen Vacancy Ni<sub><i>x</i></sub>Co<sub>3–<i>x</i></sub>O<sub>4</sub> Arrays for Ultrahigh-Capacitance Supercapacitors with Long Lifespan
Jie Sun, Yingchao Wang, Jiachao Zhou, Kang Chen, Kai Tao, Wen‐Na Zhao, Lei Han
Abstract
The amino-functionalized bimetal NH2-NiCo-MOF nanosheet array is first fabricated on Ni foam substrates and then controllably transformed into oxygen vacancy bimetal oxide arrays by simply thermal annealing in air. This NiCo-based oxide array (NixCo3–xO4/NF) achieves high capacitance (2484 F g–1 at 1 A g–1), excellent rate performance (91.4%), and long cycling life when assessed as promising electrode material for supercapacitors. Notably, the existing oxygen vacancy in NixCo3–xO4 promotes the electrochemical performance of NixCo3–xO4/NF due to the enhancement of electrical conductivity and capture capability for OH–. In addition, the assembled asymmetric supercapacitor (ASC) device exhibits an excellent energy density of 39.3 W h kg–1 at a power density of 800.2 W kg–1, which still remains 32.2 W h kg–1 even at a high power density of 7994.5 W kg–1. Furthermore, a light-emitting diode can be lightened for more than 6 min, demonstrating a great potential for practical application of ASC devices. This work knocks on the door of a feasible strategy for designing and synthesizing 2D metal oxide nanosheet arrays with excellent electrochemical properties.