Highly Nitrogen-Doped Carbon Nanotube Nanoarrays as Self-supported Bifunctional Electrocatalysts for Rechargeable and Flexible Zinc-Air Batteries

Rational design of bifunctional electrocatalysts to promote the sluggish kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) remains a fundamental challenge for the application of zinc-air batteries (ZABs). Herein, we propose a facile and cost-effective strategy to in situ grow N-doped carbon nanotubes with encapsulated FeCo alloy nanoparticles on carbon cloths (FeCo/N-CNTs@CC) as a self-supported air cathode for rechargeable ZABs. The bamboo-like FeCo/N-CNTs@CC catalyst with high nitrogen content (10.5 atom %) exhibits excellent electrocatalytic activities, including a half-wave potential of 0.816 V for ORR and an overpotential of 1.638 V for OER at 10 mA cm–2 in alkaline medium. Impressively, the liquid-state ZAB based on the FeCo/N-CNTs@CC cathode demonstrates a remarkable power density of 132.0 mW cm–2 and a stable cycling performance over 65 h. Furthermore, the flexible all-solid-state ZAB possesses outstanding performance retention under various bending conditions. The electrocatalyst presented in this work holds great potential as a self-supported air cathode for practical applications.