Non-Coalesced ZIF-8 MOF-Derived Hierarchical Porous Carbon Nanofibers for Energy Storage Applications

Abstract The development of a nitrogen-doped carbon nanofiber-incorporated 3D MOF structure as an electrode for an energy storage device has attracted significant attention for advanced electrochemical performance due to its high energy and power density. Herein, ZIF-8 was deliberately grown in situ on PAN/PVP nanofiber using an electrospinning technique to attain a hierarchically porous architecture. The integration of ZIF-8 templates and the thermal decomposition of PVP created a network of interconnected micropores and mesopores, yielding a Brunauer–Emmett–Teller (BET) specific surface area of 373.18 m2 g–1 and a maximum pore volume of 0.28 cm2 g–1. X-ray photoelectron spectroscopy (XPS) confirmed successful nitrogen doping, which significantly enhanced pseudocapacitive behavior, surface wettability, and charge-transfer kinetics in an acidic medium. The dominant surface-controlled capacitive storage mechanism (65–94%) makes the C-ZNF electrode exhibit a high specific capacitance of 278 F g–1 at 1 A g–1 in 1 M H2SO4. This unique architecture facilitates effective ion transport pathways and improves the charge storage mechanism by reducing internal resistance at the electrode–electrolyte interface. Furthermore, the symmetric coin cell-assembled device exhibits higher power density and energy density of 1000 W kg–1 and 34 Wh kg–1, respectively. The device exhibited a maximum specific capacitance of 340 F g–1 at a current density of 0.3 A g–1 (C-ZNF // C-ZNF). The device retained 84% of its initial capacitance after 5000 charge–discharge cycles. These findings demonstrate the potential of ZIF-8-derived carbon nanofiber as a promising electrode material for high-performance supercapacitors.