MOF-derived hierarchical FeCo3S4@graphitic carbon/rGO nanoarchitectures for high-energy and high-power supercapacitors

A hierarchical FeCo₃S₄@gC/rGO (Fe-Co-S@gC/rGO) hybrid nanocomposite was synthesized through a MOF-assisted solution-mediated assembly and two-step thermal treatment strategy for supercapacitor applications. The resulting architecture integrates reduced graphene oxide (rGO), graphitic carbon (gC), and cobalt sulfide-based nanostructures to improve electrical conductivity, electrolyte accessibility, and structural stability. Structural characterization confirmed the formation of a porous Fe-Co-S@gC/rGO framework with uniformly distributed Fe, Co, S, C, N, and O species. Electrochemical measurements showed that the optimized Fe-Co-S@gC/rGO electrode delivered a high specific capacitance of 1827 F g −1 at 0.5 A g −1 and retained strong cycling durability. An asymmetric supercapacitor assembled using Fe-Co-S@gC/rGO as the positive electrode and rGO as the negative electrode exhibited favorable energy-storage performance and long-term stability. The device delivered 974.1 F g⁻¹ at 0.5 A g⁻¹ and achieved a high energy density of 541.2 Wh kg⁻¹ at a power density of 8213.4 W kg⁻¹. Additionally, long-term durability was confirmed over 12,000 charge–discharge cycles and 10,000 voltammetry cycles. The enhanced electrochemical behavior is attributed to the combined effects of hierarchical porosity, conductive graphitic carbon/rGO networks, and abundant redox-active sites. These results suggest that Fe-Co-S@gC/rGO is a promising electrode material for advanced supercapacitor applications.