Metal-organic frameworks-derived honeycomb-like Co3O4/three-dimensional graphene networks/Ni foam hybrid as a binder-free electrode for supercapacitors

The honeycomb-like porous Co3O4 grown on three dimensional graphene networks/nickel foam (3DGN/ NF) has been successfully prepared by a facile solution growth process with subsequent annealing treatment, in which the Co-based metal organic framework (ZIF-67) act as the precursor of the metal oxide. The Co3O4/three-dimensional graphene networks/Ni foam (Co3O4/3DGN/NF) hybrid as the electrode for supercapacitor can deliver high specific capacitance (321 F g(-1) at 1 A g(-1)) and excellent long-cycling stability (88% of the maximum capacitance after 2000 charge-discharge cycles). Furthermore, the Co3O4/3DGN/NF hybrid exhibits the maximum energy density of 7.5 W h kg(-1) with the power density of 794Wkg(-1) and remain 4.1Wh kg(-1) with the power density of 15 kW kg(-1) in the two-electrode system. The enhanced electrochemical properties can be attributed to the unique nanostructure of Co3O4 with admirable pseudocapacitance performance and the intimate integration of graphene with the Co3O4 and the Ni foam matrix, which not only enhances the electron conductivity for fast electron and ion transport but also provides high specific surface area and excellent structural stability. (C) 2016 Elsevier B.V. All rights reserved.