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

Searching for new metal–organic frameworks with excellent electrochemical performances is considerably important to advance their application in supercapacitors. Herein, a Co 5 -cluster-based three-dimensional (3D) metal–organic framework (Co 5 (OH) 2 (O 2 CCH 3 ) 8 ·2H 2 O, Co 5 -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 Co 5 -MOF as an electrode material of supercapacitors was investigated for the first time. In a three-electrode system, the highest specific capacitance for the Co 5 -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 Co 5 -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 Co 5 -MOF particles with larger specific surface area and pore structure. Graphical abstract Co 5 -cluster-based MOF was synthesized by the solvothermal reaction, which displays excellent cyclic stability, better rate capability, and higher specific capacity as an electrode material for supercapacitors.