Synthesis of a synergistic catalyst for oxygen reduction and a Zn-air battery by the in situ coupling of hemin-derived Fe3O4/N-doped graphitic carbon

It is imperative to prepare efficient, durable materials to replace conventional expensive Pt-based electrocatalysts for the development of fuel cell technology. In this study, a simple strategy is proposed for the in situ coupling of Fe3O4 nanoparticles and nitrogen-doped graphitic carbon (Fe3O4 NPs/NGC) via the pyrolysis of hemin under argon. On account of the synergistic effects of Fe3O4 NPs and nitrogen dopants, as well as high porosity, the resulting catalyst exhibits high activity and durability toward the oxygen reduction reaction (ORR) in terms of a positive half-wave potential (0.875 V versus RHE), long-term stability (retention of 95.4% after 30 000 s), and excellent methanol tolerance. Furthermore, when Fe3O4 NPs/NGC is applied as a cathode catalyst in a Zn-air battery, it exhibits a specific capacity of 753.9 mAh g(Zn)(-1) (corresponding to a gravimetric energy density of 853.5 Wh kg(Zn)(-1)) and a maximum power density of 174.8 mW cm(-2). The results described herein will open new avenues for the design of high-performance biomolecule-based electrocatalysts.