Synthesis and synergistic electrochemical behaviour of Zn-MOF/Zn–Fe MOF composites for high-stability supercapacitor electrodes

This study investigates the synthesis and electrochemical performance of Zn-MOF and Zn–Fe MOF composites as electrode materials for high-performance supercapacitors. Metal–organic frameworks (MOFs) have attracted considerable attention for energy storage applications owing to their tunable porosity and large specific surface area; however, their inherently low electrical conductivity and susceptibility to active-site blockage remain key limitations. Electrochemical evaluation revealed that the Zn–Fe MOF electrode delivered a specific capacitance of 121.02 F g−¹ and a specific capacity of 162 mAh g−¹, compared with 108.00 F g−¹ and 32 mAh g−¹ for the pristine Zn-MOF. The composite exhibits distinct redox peaks in cyclic voltammetry, confirming faradaic charge storage behaviour, further corroborated by Electrochemical Impedance Spectroscopy (EIS). The Zn–Fe MOF electrode achieves an energy density of 4.3 Wh kg−¹ and a power density of 910 W kg−¹, while retaining 98.58% of its initial capacitance after 3000 charge–discharge cycles, demonstrating exceptional long-term stability. Dunn’s deconvolution analysis revealed that diffusion-controlled (faradaic) processes dominate at low scan rates (53% at 5 mV s−¹), whereas capacitive contributions prevail at high scan rates (94% at 200 mV s−¹). These findings establish Zn–Fe MOF composites as promising electrode materials that effectively combine structural stability with enhanced faradaic energy storage.