NiFe Alloyed Nanoparticles Encapsulated in Nitrogen Doped Carbon Nanotubes for Bifunctional Electrocatalysis Toward Rechargeable Zn‐Air Batteries

Developing cost‐effective, efficient and durable electrocatalysts to replace the high cost and low poison resistant platinum‐group‐metal (PGM) catalysts to boost the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is critical for promoting the practical performance of zinc‐air batteries (ZABs). Herein, a series of NiFe alloyed nanoparticles encapsulated in nitrogen‐doped carbon nanotubes (NixFe100−x@N‐CNTs, where x denotes the Ni ratio in NiFe alloys) have been fabricated as bifunctional catalysts for both OER and ORR. Among the series, the Ni50Fe50@N‐CNTs sample exhibited the best oxygen reversible electrocatalytic performance, of which it possessed an overpotential of 318 mV at 10 mA cm−2 for OER and a half‐wave potential of 0.86 V for ORR. The ZAB cell using Ni50Fe50@N‐CNTs as an air‐cathode also showed a power density of 203.6 mW cm−2, and a specific capacity of 778 mA h g−1, outperforming the noble‐metal‐based Pt/C+IrO2 catalyst. In addition, such ZAB cell also demonstrated a superlong stable rechargeability over 200 h without structural deterioration, presenting promises for pushing forward into practical applications. Electrocatalysis: NiFe alloyed nanoparticles encapsulated in nitrogen doped carbon nanotubes were prepared as oxygen reversible electrocatalysts for rechargeable zinc air batteries. Ni50Fe50/N‐CNTs exhibited the best OER and ORR performances in the series. When employed as air cathode, Ni50Fe50/N‐CNTs demonstrated superior properties in the primary rechargeable zinc air battery to the Pt/C+RuO2 catalyst.