Morphology-controllable synthesis of CuCo2O4 arrays on Ni foam as advanced electrodes for supercapacitors

The rational design of novel electrode materials with controllable morphologies plays a vital role in fabricating high-performance supercapacitors. In this work, a variety of CuCo2O4 arrays with different components (nanoneedle, nanosheet and nanorod) on nickel foam have been synthesized through facile hydrothermal routes. The key roles of NH4F and the alkali sources in the formation of different CuCo2O4 arrays have been discussed. As a three-electrode cell, the Ni supported CuCo2O4 nanoneedle arrays exhibit a specific capacitance of 1227.8 F g−1 at 5 mA cm−2 and capacitance retention of 95.4% after 1000 cycles, suggesting the potential application for supercapacitors. Furthermore, an asymmetric supercapacitor is fabricated with CuCo2O4 nanoneedle arrays (the anode) and activated carbon (AC) electrode (the cathode), which achieves a high energy density (31.2 W h kg−1) and excellent cycling stability (102% after 4000 cycles). Such remarkable performance is ascribed to the favorable porous structure of CuCo2O4 nanoneedle arrays which can offer abundant channels for ion diffusion and numerous active spots for reversible redox reactions. It is hoped that our work could provide inspirations for the morphology-controllable fabrications of electrode materials.