Facile preparation of flower-like NiCo2O4/three dimensional graphene foam hybrid for high performance supercapacitor electrodes

High quality flower-like NiCo2O4 has been fabricated on three-dimensional (3D) graphene foam (GF) and used as an electrode for supercapacitors. The 3D GFs are prepared through chemical vapor deposition (CVD) followed by the electro-deposition of flower-like NiCo2O4. The NiCo2O4/3D GF nanohybrids are characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy analysis. The lack of defects in the 3D GF ensures the formation high quality graphene sheets by CVD method. The supercapacitor performances of the electrode materials are evaluated through cyclic voltammetry, charge-discharge analysis and electrochemical impedance spectroscopy. A maximum specific capacitance of 1402 F g(-1) is achieved at a current density of 1 A g(-1). The NiCo2O4/3D GF nanohybrid-based supercapacitors exhibit long-cycle stability with a 76.6% retention in specific capacitance after 5000 cycles at a current density of 5 A g-1. The high electrochemical performance is attributed to the synergistic effects of the high electrical conductivity and large surface area of 3D GF along with the catalytic activity of the flower-like NiCo2O4. (C) 2015 Elsevier Ltd. All rights reserved.