Balancing Carbon Nanofiber Loading in NiFe Layered Double Hydroxides for Enhanced Oxygen Evolution Reaction

NiFe layered double hydroxides (NiFeLDHs) are highly active non-noble electrocatalysts for the oxygen evolution reaction (OER) in alkaline media, but their limited electronic conductivity restricts active-site utilization. Herein, NiFeLDH/carbon nanofiber (CNF) hybrids with different CNF contents were prepared by directly growing NiFeLDH within CNF structure to balance electronic connectivity and active-phase utilization. Catalytic activity improved with only 10 wt% CNF, while the optimal 30 wt% composition exhibited the best OER performance and enhanced interfacial charge transfer. Electrochemical impedance spectroscopy combined with distribution of relaxation times (DRT) analysis provides new insights into how the carbon network modulates interfacial electrochemical processes. The results reveal that CNF incorporation not only lowers the charge-transfer resistance but also accelerates interfacial dynamics across multiple time scales, thereby enhancing OER performance. Moreover, chronopotentiometric testing confirms stable OER operation, demonstrating that these performance gains are achieved without compromising durability.