Morphology-controllable synthesis of rod-shaped CuO@Co3O4 derived from CuCo-MOF-74 for supercapacitors

Transition metal oxides (TMOs) have excellent electrochemical properties. However, they are commonly associated with short cycle lives, agglomeration, and lower electrical conductivity. To ameliorate these drawbacks, porous rod-shaped CuO@Co3O4 has been synthesized through calcination with optimized oxidation temperature by using CuCo-MOF-74 as a template. Due to the porous structure, the CuO@Co3O4 electrode significantly increases the contact area with the electrolyte and greatly improves the reaction kinetics. As a result, the CuO@Co3O4 electrode exhibits excellent electrochemical performance with a specific capacitance of 545.5 F g−1 at a current density of 1 A g−1. The capacitance retention at 10 A g−1 was 88.7% after 10 000 cycles. Furthermore, an asymmetric supercapacitor (SC) has been assembled with CuO@Co3O4 as the positive electrode and commercial reduced graphene oxide (RGO) as the negative electrode, and the device has exhibited an energy density of 38.2 W h kg−1 at a power density of 1268.3 W kg−1. Impressively, the capacitance retention remained 83.2% even after 10 000 cycles at a high current density of 10 A g−1. This performance has demonstrated the potential of CuO@Co3O4 as an anode material for SCs.