Confining ultrasmall bimetallic alloys in porous N–carbon for use as scalable and sustainable electrocatalysts for rechargeable Zn–air batteries

Abstract

This paper demonstrates a rational protocol for the synthesis of ultrasmall bimetallic alloy nanoparticles (FeCo, FeNi, and NiCo; <4 nm) anchored on biomass-processed porous N–carbon as oxygen electrocatalysts via a micro–mesopore confinement synthetic strategy. Among them, a representative catalyst, termed FeCo–NCps, possesses highly active M–Nx–C sites, a superhigh specific surface area and a structure with abundant defects, displaying excellent bifunctional performance in both ORR and OER in 0.1 M KOH. Furthermore, a home-made rechargeable Zn–air battery was constructed using FeCo–NCps as the air cathode, delivering an excellent energy conversion efficiency (with an extremely high energy density of 922 W h kg−1 at 10 mA cm−2). This work not only provides a scalable and sustainable method to produce low-cost and highly efficient ORR/OER catalysts, but also highlights the great value of the rational design of biomass-derived nanocarbons for advanced energy materials.