N,S‐co‐doped FeCo Nanoparticles Supported on Porous Carbon Nanofibers as Efficient and Durable Oxygen Reduction Catalysts.

Finding high‐performance, low‐cost, efficient catalysts for oxygen reduction reactions (ORR) is essential for sustainable energy conversion systems. Herein, highly efficient and durable iron (Fe) and cobalt (Co)‐supported nitrogen (N) and sulfur (S) co‐doped three‐dimensional carbon nanofibers (FeCo−N, S@CNFs) were synthesized via electrospinning followed by carbonization. The as‐prepared FeCo−N,S@CNFs served as efficient ORR catalysts in alkaline 0.1 m KOH solutions that were N2 and O2‐saturated. The experimental results revealed that FeCo−N,S@CNFs were highly active ORR catalysts with defect‐rich active pyridinic N and pyrrolic N and metal bonds to N and S atom sites, which enhanced the ORR activity. FeCo−N,S@CNFs exhibited a high onset potential (Eonset=0.89 V) and half‐wave potential (E1/2=0.85 V), similar to the electrocatalytic activity of commercial Pt/C. Additionally, the durability of the as‐prepared FeCo−N,S@CNFs catalysts was maintained for 14 h with long‐term stability and high tolerance to methanol stability, accounting for their excellent catalytic ability. Furthermore, Co−N@CNFs, Fe−N@CNFs, and varying Fe and Co ratios were compared with those of FeCo−N,S@CNFs. Synergistic interactions between metals and heteroatoms were believed to play a significant role in enhancing the ORR activity. Owing to their excellent catalytic reduction ability, the as‐prepared FeCo−N,S@CNFs can be widely used in battery‐based systems and replace commercial Pt/C in fuel cell applications. [ABSTRACT FROM AUTHOR]