Rational assembly of hybrid carbon nanotubes grafted on the carbon nanofibers as reliable and robust bifunctional catalyst for rechargeable zinc-air battery

Abstract

Research on extremely efficient bifunctional electrocatalysts to promote both the sluggish oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) kinetics is of paramount importance for the advanced rechargeable Zinc-air battery. Herein, a cost-effective and scalable strategy is proposed for the synthesis of FeCo alloy nanoparticles embedded in the nitrogen-doped carbon nanotubes-grafted nitrogen and sulfur co-doped carbon nanofibers (FeCo-NSCNF@NCNT). The newly obtained catalyst with three-dimensional (3D) interconnected network architecture demonstrates high ORR and OER catalytic activities as evidenced by the high half-wave potential for the ORR and a low overpotential for the OER, which can be comparable to the commercially available well-known precious metal catalysts. With the catalyst employed as the air electrode of an assembled Zinc-air battery, narrow charge-discharge voltage gap and superb cycling stability (over 100 h) at the current density of 10 mA cm−2 can be obtained, signifying the promising application in the next generation of rechargeable metal-air batteries.