1D bamboo-like N-doped carbon nanotubes with encapsulated iron-based nanoparticles as an advanced Zn-air battery cathode electrocatalyst

Abstract

Developing low-cost nonprecious metal catalysts with excellent activity and high durability for oxygen reduction reaction (ORR) is greatly imperative but challenging. Here, a high-performance ORR catalyst is designed based on in-situ grown bamboo-like N-doped carbon nanotubes with encapsulated Fe-based nanoparticles (Fe@B-NCNTs). The architecture of the 1D hierarchical porous nanotubes, large surface area with abundant defects and active sites, and strong coupling interactions between the enclosed metal-cluster core and the N-doped graphitic carbon shell synergistically enhance the electrocatalytic activity. As a result, Fe@B-NCNTs exhibit a more positive half-wave potential (0.898 V vs. the reversible hydrogen electrode, RHE), higher electrochemical stability and more superior resistance to methanol crossover than those of Pt/C in an alkaline electrolyte. Interestingly, when acting as a cathode electrocatalyst for a primary Zn-air battery (ZAB), Fe@B-NCNTs display a peak power density of ∼147 mW cm−2 and a first-class specific energy density of ∼921 Wh kgZn−1 at a discharge current density of 20 mA cm−2. Moreover, a proof-of-concept solid-state ZAB with bendable ability demonstrates the application potential in portable and wearable electronic devices.