An Investigation of the Electrochemical Properties of CuCo 2 O 4 @NiCo 2 O 4 Composite as Binder-Free Electrodes of a Supercapacitor

Metallic oxides are considered promising candidates for supercapacitors owing to their inherent pseudocapacitive behavior and superior electrochemical properties. In this work, NiCo 2 O 4 , CuCo 2 O 4 , and CuCo 2 O 4 @NiCo 2 O 4 composite electrodes are synthesized directly on a nickel foam substrate via the facile hydrothermal method. The phase of the prepared materials was analyzed using the X-ray diffraction method. The morphology of the prepared binder-free electrodes was observed by scanning electron microscopy. The electrochemical testing was done in a 2 M KOH solution against an Ag/AgCl reference electrode. The CuCo 2 O 4 @NiCo 2 O 4 composite electrode demonstrated a value of specific capacitance as high as 422 F g −1 at a current density of 1 A g −1 and thus outperformed the NiCo 2 O 4 and CuCo 2 O 4 in terms of its electrochemical performance. The CuCo 2 O 4 @NiCo 2 O 4 composite retained a specific capacitance of 278 F g −1 even with the increase of current density to 10 A g −1 , which corresponds to a 34% loss of capacitance compared to 40% and 48% of individual NiCo 2 O 4 and CuCo 2 O 4 electrodes, respectively. Hence, the synergy in a composite material demonstrates it to be a potential candidate as an electrode in supercapacitors.