A Self-Jet Vapor-Phase Growth of 3D FeNi@NCNT Clusters as Efficient Oxygen Electrocatalysts for Zinc-Air Batteries.

Development of highly active, robust electrocatalysts to accelerate the sluggish oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is crucial and challenging for the practical application of metal-air batteries. In this effort, a novel and facile self-jet vapor-phase growth approach is developed, from which highly dispersive FeNi alloy nanoparticles (NPs) encapsulated in N-doped carbon nanotubes (NCNT) grown on a cotton pad (FeNi@NCNT-CP) can be fabricated. The as-prepared FeNi@NCNT-CP clusters exhibit superior bifunctional catalytic activity, with a high half-wave potential of 0.85 V toward ORR and a low potential of 1.59 V at 10 mA cm-2 toward OER. Specifically, owing to the synergistic effects of FeNi alloy NPs and NCNT, FeNi@NCNT-CP clusters deliver excellent stability, demonstrating a small potential gap of 0.73 V between ORR and OER after operation for 10 000 cycles. Furthermore, FeNi@NCNT-CP serves as a cost-effective, superior catalyst for the cathode of a rechargeable Zn-air battery, outperforming a catalyst mixture of expensive Pt/C and IrO2 . FeNi@NCNT-CP provides a maximum power density of 200 mW cm-2 and a cycling stability of up to 250 h. This contribution provides new prospects to prepare non-noble electrocatalysts for metal-air battery cathodes.