Zero-valence Fe boosts the activity of Fe-N-C electrocatalyst in oxygen reduction reaction

Constructing non-noble metal-based catalysts has attracted more attention owing to these materials owning high abundance, low cost, and expected to take the place of Pt/C as a candidate commercial the oxygen reduction reaction (ORR) catalyst. Herein, hollow microspheres self-assembled by a layer of interweaving Fe2O3 nanorods are first fabricated by a one-step hydrothermal process, which are then covered by dopamine. Finally, annealing treatment at the assigned temperature in N-2 is conducted to synthesize Fe/FexOy nanorod-based hollow microspheres (similar to 900 nm in diameter) covered by N-doped carbon. Electrochemical measurements demonstrate that, by the side of the commercial 20% Pt/C, the as-obtained T-650 has a higher onset potential (83-mV positive shift), more positive half wave potential (55-mV positive shift), and larger limiting current density (increased by 0.9 mA cm(-2)). It is found that the simultaneous presence of zero-valence Fe and nitrogen atoms is the key to the high catalytic activity of the as-synthesized Fe-N-C material, and these unique hierarchical hollow porous microspheres make the electrocatalyst possess excellent catalytic performance, long-time stability, and superior methanol tolerance.