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

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 m(2) 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.