Two-Dimensional Fe-N-C Nanosheets for Efficient Oxygen Reduction Reaction

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Fe-N-doped carbon (Fe-N-C)-based electrocatalysts are considered to be promising alternatives to replace Pt-based catalysts for oxygen reduction reactions (ORR). Here, we reported a simple and effective approach to prepare Fe-N-C-based electrocatalysts with the shape of two-dimensional nanosheets (termed Fe/NCNSs) to enhance the ORR performance. Fe/NCNSs were prepared by the calcination of Fe/Zn dual-metal ZIFs nanosheets as precursors. Benefiting from its higher specific surface area, electrochemically active surface area, and proportion of pyridinic N and Fe-N, the optimized Fe/NCNS showed excellent ORR performance both in acidic (E1/2 = 0.725 V vs. RHE) and alkaline (E1/2 = 0.865 vs. RHE) media, being 23 mV more negative and 24 mV more positive than that of a commercial Pt/C. The optimized Fe/NCNS also exhibited long durability. In addition, the Zn-air battery with Fe/NCNS-1 and RuO2 as the air catalyst exhibited high power density (1590 mW cm−2 at a current density of 2250 mA cm−2) and superior charging/discharging durability.