Nanoforest of hierarchical Co3O4@NiCo2O4 nanowire arrays for high-performance supercapacitors

Nanoforest of hierarchical Co3O4@NiCo2O4 nanowire arrays were synthesized via a facile strategy for electrochemical supercapacitors. The smart combination of Co3O4 and NiCo2O4 nanostructures in the nanowire arrays shows a promising synergistic effect for capacitors with greatly enhanced performance. A high areal capacitance of 2.04 F cm(-2) at the scan rate of 5 mV s(-1) and 0.79 F cm(-2) (almost 2.5 times as high as that of pristine Co3O4) even at 30 mA cm(-2) after 6000 cycles with varying current densities were achieved. Particularly, when the current turned back to 10 mA cm(-2) after the above cycles with large current, 1.18 F cm(-2), corresponding to 83.7% of the initial capacitance, can be recovered and maintains for another 1500 cycles without noticeable decrease. These results show that the nanoforest of hierarchical Co3O4@NiCo2O4 nanowire arrays could be a promising electrode material for high-performance electrochemical capacitors. (C) 2013 Elsevier Ltd. All rights reserved.