FeCo Nanoparticles Encapsulated in N-Doped Carbon Nanotubes Coupled with Layered Double (Co, Fe) Hydroxide as an Efficient Bifunctional Catalyst for Rechargeable Zinc-Air Batteries.

Low-cost bifunctional nonprecious metal catalysts toward oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are critical for the commercialization of rechargeable zinc-air batteries (ZABs). However, the preparation of highly active and durable bifunctional catalysts is still challenging. Herein, an efficient catalyst is reported consisting of FeCo nanoparticles embedded in N-doped carbon nanotubes (FeCo NPs-N-CNTs) by an in situ catalytic strategy. Due to the encapsulation and porous structure of N-doped carbon nanotubes, the catalyst shows high activity toward ORR and excellent durability. Furthermore, to enhance the OER activity, CoFe-layer double hydroxide (CoFe-LDH) is coupled with FeCo NPs-N-CNTs by in situ reaction approach. As the air electrode for rechargeable ZABs, the cell with CoFe-LDH@FeCo NPs-N-CNTs catalyst exhibits high open-circuit potential (OCP) of 1.51 V, high power density of 116 mW cm-2 , and remarkable durability up to 100 h, demonstrating its great promise for the practical application of the rechargeable ZABs.