Metal–organic framework-derived hybrid of Fe3C nanorod-encapsulated, N-doped CNTs on porous carbon sheets for highly efficient oxygen reduction and water oxidation

Abstract

Active and stable electrocatalysts based on earth-abundant elements for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are crucially important for the utilization of renewable energy. Herein, we reported the synthesis of Fe₃C nanorod encapsulated, N-doped carbon nanotubes grown on N-doped porous carbon sheets (Fe₃C@NCNT/NPC) by simply annealing a Fe-based MOF (MIL-88B) loaded with melamine at 800 °C in N₂. Thanks to the synergistic effect of the high density of Fe–N active sites and electric conductance offered by the unique hybrid structure, the as-prepared Fe₃C@NCNT/NPC hybrid exhibited a half-wave potential ca. 60 mV more positive and a durability performance much better than that of Pt/C for ORR, and an overpotential ca. 20 mV lower and a Tafel slope much smaller than that of IrO₂ for OER, which make it one of the best reported nonprecious metal bifunctional electrocatalysts for oxygen electrode reactions.