Fe–Cu Bimetallic Metal–Organic Framework/Graphene Hybrid Electrodes for Advanced Supercapacitor Applications

In recent years, metal–organic frameworks (MOFs) have gained significant attention as efficient electrode materials for supercapacitors owing to their high specific surface area, tunable porous structure, and unique physicochemical properties. Herein, we demonstrate solvothermal synthesis of bimetallic Fe–Cu MOFs using iron and copper precursors and 2-aminoterephthalic acid as the organic linker. In order to overcome the inherent low electrical conductivity of MOFs, hybrids were prepared by incorporating reduced graphene oxide (rGO) at varying weight percentages. The main objective of the present study is to prepare supercapacitor electrodes by integrating the highly pseudocapacitive activity of the Fe–Cu MOFs with the excellent electrical properties of reduced graphene oxide. UV–vis, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and energy dispersive X-ray spectroscopy (EDS) characterization techniques confirmed the successful preparation of the Fe–Cu MOF/rGO hybrid. Electrochemical characterization showed that the FCG-10 (Fe–Cu MOF–10 wt % rGO) hybrid electrode exhibited a specific capacitance of 814.60 F g–1 at a scan rate of 5 mV s–1. Galvanostatic charge–discharge (GCD)-derived specific capacitance was found to be 706.85 F g–1 at 1 A g–1 in a three-electrode configuration. The FCG-10//rGO asymmetric supercapacitor, assembled using 1.30 mg of FCG-10 and 1.60 mg of rGO, showed a device-specific capacitance of 174.07 F g–1, an energy density of 28.19 Wh kg–1, and a power density of 539.80 W kg–1 at 1 A g–1. The FCG-10 electrode retained 91.8% of its initial capacitance after 10,000 GCD cycles in the three-electrode configuration. In a separate two-electrode FCG-10//rGO asymmetric device, the device retained 89.23% of its capacitance after 6000 cycles. The enhanced electrochemical performance can be ascribed to the synergistic effect of the highly porous Fe–Cu MOF and conductive reduced graphene oxide (rGO). The promising results demonstrate that the proposed approach provides an effective platform for the development of next-generation supercapacitor devices.