A three-dimensional Co5-cluster-based MOF as a high-performance electrode material for supercapacitor

Abstract

Searching for new metal–organic frameworks with excellent electrochemical performances is considerably important to advance their application in supercapacitors. Herein, a Co5-cluster-based three-dimensional (3D) metal–organic framework (Co5(OH)2(O2CCH3)8·2H2O, Co5-MOF) was synthesized and characterized by X-ray powder diffraction, infrared spectroscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy, scanning electron microscopy, and nitrogen adsorption–desorption. The Co5-MOF as an electrode material of supercapacitors was investigated for the first time. In a three-electrode system, the highest specific capacitance for the Co5-MOF electrode is 867 F g−1 at 1 A g−1, and the specific capacitance still remains 90.3% of the original specific capacitance after 3000 cycles, displaying its good long-term cycle stability. The asymmetric supercapacitor based on the Co5-MOF as the positive electrode and the rGO as the negative electrode presented a high energy density of 18 W h kg−1 at a power density of 0.7 kW kg−1. The high supercapacitive properties may be attributed to the nano-sized Co5-MOF particles with larger specific surface area and pore structure.