Covalent organic polymer derived N–doped carbon confined FeNi alloys as bifunctional oxygen electrocatalyst for rechargeable zinc-air battery

Abstract

N–doped carbon confined FeNi alloys are promising candidate to noble Pt and IrO2 or RuO2 for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in rechargeable zinc-air batteries. However, it is difficult to control the distribution of transition metals in the precursor and electrocatalyst. Herein, we design a covalent organic polymer to realize the uniform distribution of metal, nitrogen and carbon precursors. The structure of the obtained electrocatalyst is FeNi nanoparticles coated with carbon shells dispersed on N-doped multilayer porous carbon (FeNi@NC). The resultant FeNi@NC delivered a half-wave potential for ORR of 0.878 V and a low potential of 1.59 V to achieve 10 mA cm−2 for OER, which surpasses commercial platinum/carbon and ruthenium dioxide. The outstanding bifunctional properties of FeNi@NC attribute to the synergistic coupling between N-doped carbon shells and dense FeNi nanoparticles. Moreover, the self-made zinc-air battery with FeNi@NC air-cathode displayed an excellent energy density of 137.7 mW cm−2 as well as cycling stability (100 h, 200 cycles).