Electrochemical synthesis of CuCo2O4 nanosheets on Ni foam as a binder-free electrode for supercapacitors

In recent years, supercapacitors have attracted great attention as high-power energy sources due to their fast charge-discharge rate, high power density, long cyclelifetime and high reliability [1]. Recently binary metal oxides such as spinels are emerging as new electrode materials owning to their rich redox reactions [2]. In this study, for the first time, we developed a facile electrodeposition method combined with post-annealing to grow ultrathin CuCo2O4 nanosheets on Ni foam substrate as a binder-free electrode for supercapacitors. In a typical synthesis, 0.2 mmol of copper nitrate and 0.4 mmol of cobalt nitrate were dissolved in 25 mL of DI water and a potential of −1.0 V (vs. Ag/AgCl ) was applied to deposit Cu–Co hydroxide precursor. After electrodeposition for 10 min, the as prepared electrode was rinsed several times with deionized water. Finally, in order to get crystallized CuCo2O4 nanosheets, the sample was annealed in air at 300 ℃ for 2 h. The FESEM image (Fig. 1) confirms the preparation of CuCo2O4 nanosheets. The results of electrochemical measurements revealed that the CuCo2O4 electrode has a high specific capacitance of 1330 F g-1 at a current density of 2 A g-1 with 93.6 % specific capacitance retention after 5000 cycles. Owing to the unique structural features, the as obtained CuCo2O4 nanosheet is considered as an effective electrode for the next generation energy storage device