Ni3Fe-N Doped Carbon Sheets as a Bifunctional Electrocatalyst for Air Cathodes

A promising bifunctional electrocatalyst is reported for air cathodes consisting of Ni3Fe nanoparticles embedded in porous nitrogen-doped carbon sheets (Ni3Fe/N-C sheets) by a facile and effective pyrolysis-based route with sodium chloride (NaCl) crystals as a template. The Ni3Fe/N-C sheets show excellent catalytic activity, selectivity, and durability toward both the oxygen-reduction and oxygen-evolution reactions (ORR and OER). They are shown to provide a superior, low-cost cathode for a rechargeable Zn-air battery. At a discharge-charge current density of 10 mA cm(-2), the Ni3Fe/N-C sheets enable a Zn-air battery to cycle steadily up to 420 h with only a small increase in the round-trip overpotential, outperforming the more costly Pt/C + IrO2 mixture catalyst (160 h). With the simplicity and scalability of the synthetic approach and its remarkable bifunctional electrocatalytic performance, the Ni3Fe/N-C sheets offer a promising rechargeable air cathode operating at room temperature in an alkaline electrolyte.