Achieving efficient oxygen reduction on ultra-low metal-loaded electrocatalysts by constructing well-dispersed bimetallic sites and interconnected porous channels

Developing highly efficient, stable, and earth-abundant electrocatalysts for the oxygen reduction reaction (ORR) is crucial for practical energy conversion devices, especially for fuel cells and metal-air batteries. Electrocatalysts with porous structures, effective composition and easily accessible active sites are extremely desirable in this tri-phase reaction. Herein, a three-dimensional hierarchically porous N-doped carbon nanofibers anchored with well-dispersed FeCo site (FeCo@PCNF) composite electrocatalyst is fabricated by a scalable electrospinning method followed by carbonization. The hierarchically porous architecture filled with interconnected channels and interlaced porosity provides the large surface area and rich exposed active sites of FeCo@PCNFs, hence, achieving accelerated mass transfer and improved ORR electrocatalytic ability. The electrocatalyst displays a more positive onset potential of 0.97 V-RHE (RHE: versus the reversible hydrogen electrode) and half-wave potential of 0.875 V-RHE under alkaline conditions, superior to commercial Pt/C. Moreover, FeCo@PCNFs exhibits good stability and tolerance to methanol. Impressively, when being used as an air-cathode in primary zinc-air batteries, FeCo@PCNFs presents a higher peak power density of 289.5 mW cm(-2) with excellent stability than Pt/C and most reported materials.

Automated summary

A three-dimensional hierarchically porous N-doped carbon nanofibers anchored with well-dispersed FeCo site composite electrocatalyst has been developed, showing superior ORR catalytic performance and higher peak power density with excellent stability as an air-cathode in primary zinc-air batteries.