A facile one-step synthesis of the hybrid of hierarchical nitrogen-doped porous carbon and Fe₃C nanoparticles encapsulated a nitrogen-doped carbon nanotube through simply annealing the mixture of FeCl₃, o-phthalic anhydride, and melamine at 800 °C in Ar was proposed. Both the specific ratio of these precursors and the selected annealing temperature are key factors for the formation of the unique hybrid structure, while any subtle modulation will result in different morphologies. Thanks to the good conductivity and hierarchical porous diversity, Fe−N−C material obtained at 800 °C exhibits a half-wave potential of 0.880 V, ca. 50 mV more positive than Pt/C, for oxygen reduction reaction (ORR) and an overpotential of 0.41 V, ca. 36 mV lower than IrO₂ black, at the current of 10 mA cm⁻² for oxygen evolution reaction (OER).

        https://doi.org/10.1021/acs.jpcc.6b03070