Freestanding 1D Hierarchical Porous Fe‐N‐Doped Carbon Nanofibers as Efficient Oxygen Reduction Catalysts for Zn–Air Batteries

Abstract

High‐performance nonprecious metal‐doped 1D carbon catalysts for oxygen reduction reactions (ORR) are viable candidates in lieu of platinum‐based catalysts. Hierarchical porous Fe‐N‐doped carbon nanofibers (Fe‐NHCFs) are fabricated via carbonization of MOF nanofibers with a specific surface area of 294 m2 g−1 and inherent hierarchical porosity. Benefiting from the Fe‐N doping‐induced active sites, unique hierarchical porosity, and 1D honeycomb conductive networks to facilitate electron transfer, the freestanding Fe‐NHCFs confer a current density (5.2 mA cm−2) at 0.70 V (vs reversible hydrogen electrode), comparable with the commercial 20 wt% Pt/C (5 mA cm−2) in alkaline medium. Especially, the parallel characteristics with Pt/C is acquired in an assembled Zn–air battery, which deliver a discharge current density of 90 mA cm−2 and an output peak power density of 61 mW cm−2. This simple synthesis strategy would leverage a new geometry for tailored utility of active sites for ORR in a 1D carbon framework.