Hierarchical graphene oxide/Co-metal-organic framework/Fe₃O₄ structures for high-performance applications

Abstract

Metal–organic frameworks (MOFs) and ferrites face drawbacks such as poor conductivity and self-aggregation. Optimized synthesis methods partially alleviate these issues, while a complementary strategy is to design nanocomposites that integrate both materials. We engineer three-dimensional hierarchically porous nanoparticles, where graphene nanosheets act as a robust substrate that tightly encapsulates Co-MOF/Fe₃O₄ nanoparticles. This architecture increases active sites, enhances the electrode–electrolyte interfacial area, improves electron conductivity, and prevents aggregation during charge–discharge cycling. The heterogeneous structure optimizes reaction kinetics, while the graphene nanosheets provide abundant electroactive sites, boosting electrochemical performance. Electrochemical measurements show a specific capacitance of 1710 F g⁻¹ at 0.5 A g⁻¹ in a three-electrode configuration. As a supercapacitor electrode, the material delivers 869 F g⁻¹ at 0.5 A g⁻¹, an energy density of 212.2 Wh kg⁻¹ at a power density of 8905 W kg⁻¹, and 96.8% capacity retention after 10,000 cycles, demonstrating significant promise as an innovative electrode material. This study introduces a hierarchical GO/Co-MOF/Fe₃O₄ hybrid synthesized through a two-step solvothermal process, providing an integrated conductive and redox-active framework that achieves outstanding electrochemical performance, achievement of high specific capacitance, and excellent cycling stability due to synergistic ion- and electron-transport pathways. Schematic illustration of the synthesis route and electrochemical mechanism of the hierarchical GO/Co-MOF/Fe3O4 composite electrode.