High specific surface area ZnO/ZIF-67 nanostructures as supercapacitor electrode

In this study, ZnO/ZIF-67 was synthesized on nickel foam and subsequently evaluated for its chemical behavior using a three-electrode system in a 2 mol L^–1 KOH electrolyte. Cyclic voltammetry and galvanostatic charge and discharge analysis measurements were employed. At a current density of 1 A g^–1, ZnO/ZIF-67 exhibited the highest specific capacitance of 2908 F g^–1. The suggested electrode demonstrated excellent cycle stability, maintaining its performance over 5000 charge–discharge cycles. Furthermore, the retention capacity of ZnO/ZIF-67 was determined to be 95.3%, accompanied by an approximate 100% coulombic efficiency. Subsequently, an asymmetric supercapacitor was constructed to investigate the system's capacitive behavior. The maximum specific capacitance of the two-electrode device was obtained as 264.4 F g^–1 at a current density of 1 A g^–1, with approximately 78.8% of the capacitance retained even after 5000 charge–discharge cycles. These results highlight the potential utilization of ZnO/ZIF-67 nanostructures in advancing the development of next-generation supercapacitors.