Sequential MOF-Derived Strategy for Uniformly Dispersed ZnO/Co ₃ O ₄ Nanocrystals in Porous Carbon Nanofibers for Supercapacitors

The development of advanced electrode materials with high specific capacitance and energy density with a long cycle life is critical for next-generation supercapacitors. In this study, we report a composite material comprising nitrogen-doped hierarchical porous carbon nanofibers (PCNFs) embedded with ZnO/Co 3 O 4 nanocrystals, which are encapsulated by a few turbostratic carbon layers. These were synthesized via a sequential strategy using a combination of monometallic (ZIF-8) and bimetallic (Zn/Co ZIFs) metal–organic frameworks, yielding distinct morphologies. The optimized composite electrode demonstrated a specific capacitance of 1066 F g –1 at 1 A g –1 in a three-electrode setup and retained 83% of its capacitance after 10,000 cycles. When assembled in an asymmetric supercapacitor cell, the material achieved an impressive energy density of 19.86 Wh kg –1 at a power density of 50 W kg –1 . The outstanding performance is attributed to the synergistic effects of the conductive turbostratic carbon matrix and the pseudocapacitive ZnO/Co 3 O 4 nanocrystals within the hierarchically porous structure. This work presents a solution-processable and potentially scalable strategy for designing MOF-derived carbon nanostructures for high-performance energy-storage applications.