Excellent electrochemical stability of Co₃O₄array with carbon hybridization derived from metal-organic framework

Hybrid supercapacitors have attracted considerable attention for the use in the energy storage systems due to the simultaneous possession of high power and energy. Herein, Co₃O₄array with amorphous carbon on Ni foam has been derived from the Co-MOF. The electrochemical dynamics and energy storage mechanism of the prepared electrode have been investigated, which reveals the enhancement of the capacitive behavior with the scan rate. The electrochemically active specific surface area (ECSA) of our sample is calculated as 1416 cm²for per square centimeter of electrode. The prepared material exhibits an excellent electrochemical performance (3.17 F · cm^-2at 1 mA · cm^-2and 2.076 F · cm^-2at 30 mA · cm^-2). Further, the long-term life shows 96.7% capacity retention at 50 mV · s^-1after 20 000 cycles in KOH aqueous electrolyte. The Coulomb efficiency is noted to range from 95% to 100% even after 20 000 cycles. Further, the symmetrical solid-state supercapacitor represents a wide operating voltage range and high scan rate for practical applications. Three charged solid-state supercapacitors are observed to lit 160 parallel green LEDs (20 mA, 2.2V) for approximately 50 s. These findings from this study confirm the potential of Co₃O₄array with carbon hybridization as an effective supercapacitor electrode material.