Hierarchical Cu0.27Co2.73O4/MnO2 nanorod arrays grown on 3D nickel foam as promising electrode materials for electrochemical capacitors†
Abstract
Cu0.27Co2.73O4/MnO2 hybrid hierarchical nanostructure arrays directly on pressed nickel foam, with thin MnO2 nanoflakes homogeneously wrapped on Cu0.27Co2.73O4 nanorod arrays, are successfully synthesized by a simple hydrothermal and post heat-treatment method. The microstructures, phase structure, crystalline state, chemical components and chemical bonding state of the hybrids are systematically characterized using XRD, XPS, SEM and TEM. The electrochemical performance of the Cu0.27Co2.73O4/MnO2 hybrid electrode for electrochemical capacitors (EC) is investigated using cyclic voltammetry (CV), galvanostatic charge–discharge and electrochemical impedance spectroscopy (EIS) techniques. A superior areal capacitance of ∼4 F cm−2 is obtained for the Cu0.27Co2.73O4/MnO2 hybrid electrode even at a high current density of ∼18.6 mA cm−2. The 3D Cu0.27Co2.73O4/MnO2 hierarchically porous nanorod array structures endow the electrodes with a large specific surface area and improve the pathway for ion diffusion, thus leading to high areal capacitance and excellent rate capability, and indicate their promising application as binder-free electrodes for high performance EC and potentiality triggering the exploration of improved areal capacitance for miniaturized devices.
- This article is part of the themed collection: 2015 Journal of Materials Chemistry A Hot Papers