Bifunctional MOF-5/FeCo ₂ O ₄ Hybrid Nanostructures for High-Performance Supercapacitors and Hydrogen Evolution Reactions

The synthesis strategy plays a crucial role in tuning nanoscale features such as surface area, porosity, and active site density, which directly influence electrocatalytic performance. In this work, a porous MOF-5/FeCo 2 O 4 nanocomposite was synthesized via solvothermal and solution combustion methods, exhibiting a nanofiber-embedded cubic architecture with abundant active sites. The composite demonstrated excellent HER performance in 0.5 M H 2 SO 4, delivering a low overpotential of 0.197 V at 10 mA cm –2 and a small Tafel slope of 35 mV dec –1, outperforming pristine FeCo 2 O 4 . In a three-electrode configuration, the material exhibited a high specific capacitance of 822 F g –1 at 6 A g –1 . Furthermore, a symmetric two-electrode supercapacitor device delivered a specific capacitance of 173.43 F g –1, an energy density of 15 Wh kg –1, and a power density of 3000 W kg –1, with 66% capacitance retention and 89% Coulombic efficiency after 10,000 cycles. The enhanced performance is attributed to the synergistic integration of MOF-5 and FeCo 2 O 4, providing improved conductivity, abundant active sites, and efficient ion transport, making it a promising bifunctional material for energy storage and hydrogen evolution applications.