In situ construction of FeCo alloy nanoparticles embedded in nitrogen-doped bamboo-like carbon nanotubes as a bifunctional electrocatalyst for Zn-air batteries.

ABSTRACT

The rational design and exploration of low-cost, highly efficient, and robust bifunctional oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) electrocatalysts are essential for the application of zinc-air batteries. Herein, a novel highly active and stable oxygen electrode catalyst is designed based on in situ construction of FeCo alloy nanoparticles embedded in nitrogen-doped carbon nanotubes (FeCo/N-CNTs-800) with a bamboo-like structure. The unique architecture of bamboo-like nanotubes, the large surface area with abundant mesoporous structure, and the strong coupling interactions between the encapsulated alloy nanoparticle core and the nitrogen-doped graphitic carbon shell synergistically enhance the electrocatalytic activity. As a result, FeCo/N-CNTs-800 exhibits remarkable ORR (with a half-wave potential of 0.891 V in 0.1 M KOH) and OER (with an overpotential of 359 mV to deliver 10 mA cm-2 in 1 M KOH) performance, respectively. More impressively, an assembled zinc-air battery with the bifunctional FeCo/N-CNTs-800 catalyst as the air electrode demonstrates a large power density of 200.4 mW cm-2 and robust cycling performance over 445 h compared to precious-metal catalysts Pt/C∥IrO2. Thus, the electrocatalyst presented in this work holds great potential as an air cathode for practical applications of zinc-air batteries.