Suppressing Thermal Migration by Fine‐Tuned Metal‐Support Interaction of Iron Single‐Atom Catalyst for Efficient ORR

Abstract

AbstractAtomically dispersed iron–nitrogen–carbon (FeNC) catalysts have sparked great interest by virtue of the highly active isolated FeN4 sites. The catalysts with pyrolysis treatment usually induce inevitable FeN4 sites agglomeration, leading to fast degradation in catalytic activity. Herein, a pre‐coordinated protection strategy is proposed to eliminate the aggregation of Fe atoms by suppressing the thermal migration during the pyrolysis process. To this end, the S atom is introduced into the graphitic support by enhancing the metal‐support interaction. The proposed atomic structure is revealed by multiple advanced characterizations including Fe Mössbauer spectroscopy, X‐ray absorption spectroscopy, and theoretical calculations. By employing S atom into the structure, the center atom Fe is oxidized to a higher valence, improving the bonding energy with the graphitic support, which accordingly endows catalyst anti‐sintering capacity and improved catalytic activity. Compared to commercial Pt/C and the reported catalyst with secondary pyrolysis, the proposed catalysts exhibit enhanced ORR activity in alkaline media (E1/2 = 0.91 V). This work provides a new avenue toward optimizing and improving ORR performance of atomically dispersed Fe catalysts.