Mesopore‐Rich Fe–N–C Catalyst with FeN4–O–NC Single‐Atom Sites Delivers Remarkable Oxygen Reduction Reaction Performance in Alkaline Media

Abstract

Fe–N–C catalysts offer excellent performance for the oxygen reduction reaction (ORR) in alkaline media. With a view toward boosting the intrinsic ORR activity of Fe single‐atom sites in Fe–N–C catalysts, fine‐tuning the local coordination of the Fe sites to optimize the binding energies of ORR intermediates is imperative. Herein, a porous FeN 4–O–NCR electrocatalyst rich in catalytically accessible FeN 4–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) is reported. Fe K‐edge X‐ray absorption spectroscopy (XAS) verifies the presence of FeN 4–O active sites in FeN 4–O–NCR, while density functional theory calculations reveal that the FeN 4–O coordination offers a lower energy and more selective 4‐electron/4‐proton ORR pathway compared to traditional FeN 4 sites. Electrochemical tests validate the outstanding intrinsic activity of FeN 4–O–NCR for alkaline ORR, outperforming Pt/C and almost all other M–N–C catalysts reported to date. A primary zinc–air battery constructed using FeN 4–O–NCR delivers a peak power density of 214.2 mW cm−2 at a current density of 334.1 mA cm−2, highlighting the benefits of optimizing the local coordination of iron single atoms.