Mesopore-rich Fe-N-C catalyst with FeN 4 -O-NC Single Atom Sites Delivers Remarkable Oxygen Reduction Reaction Performance in Alkaline Media

Fe-N-C catalysts offer excellent performance for the oxygen reduction reaction (ORR) in alkaline media. With a view towards boosting the intrinsic ORR activity of Fe single atom sites in Fe-N-C catalysts, fine-tuning the local coordination of Fe sites to optimize the binding energies of ORR intermediates is imperative. Here we report the successful synthesis of a porous FeN -O-NCR electrocatalyst rich in catalytically accessible FeN -O sites (wherein the Fe single atoms are coordinated to four in-plane nitrogen atoms and one subsurface axial oxygen atom) supported on N-doped carbon nanorods (NCR). Fe K-edge X-ray absorption spectroscopy (XAS) verified the presence of FeN -O active sites in FeN -O-NCR, whilst density functional theory calculations revealed that the FeN -O coordination offered a lower energy and more selective 4-electron/4-proton ORR pathway compared to traditional FeN sites. Electrochemical tests validated the outstanding intrinsic activity of FeN -O-NCR for alkaline ORR, outperforming both Pt/C and almost all other M-N-C catalysts reported to date. A primary zinc-air battery constructed using FeN -O-NCR delivered a peak power density of 214.2 mW cm at a current density of 334.1 mA cm , highlighting the benefits of fine-tuning the local coordination of the iron single atoms. This article is protected by copyright. All rights reserved.