Abstract
<title>Abstract</title> <p> Despite considerable progress in electrochemical energy storage, the simultaneous attainment of high energy density, superior rate capability, and robust long-term cycling stability in electrode materials remains a critical bottleneck to advancing supercapacitor technology toward practical deployment. This study synthesized a dual zeolitic imidazolate framework (ZIF-8/ZIF-67)-derived Fe/Co/Zn oxide embedded in a carbon matrix via solvothermal treatment followed by carbonization. Electrochemical analyses demonstrated significant pseudocapacitive activity. Fe/Co/Zn-400 demonstrated enhanced electrochemical performance, achieving a maximum specific capacitance of 1070 F/g (367 C/g) at 0.5 A/g. The kinetic study demonstrated b-values of 0.57–0.63, indicating predominantly pseudocapacitive charge-storage characteristics. The Dunn analysis revealed capacitive and diffusion-controlled contributions. An asymmetric two-electrode device utilizing Fe/Co/Zn-400 exhibiting a maximum specific capacitance of 95 F/g and an energy density of 36 Wh/kg at a power density of 480 W/kg. Moreover, the device maintained approximately 80% of its original capacitance over 1500 cycles, with 100% coulombic efficiency. For HER in KOH (1 M), Fe/Co/Zn-300, and Fe/Co/Zn-400 offered overpotentials of 70 mV and 354 mV at 50 mA/cm <sup>2</sup> , respectively. Chronoamperometric analysis indicates that the materials remain stable for 18 hours with only a negligible decrease in activity. </p>