Intrinsic Defect-Rich Carbon-Supported Iron Phthalocyanine as Beyond-Pt Oxygen Reduction Catalysts for Zinc-Air Batteries

Molecular iron phthalocyanine (FePc) bearing a single-atom Fe-N4 moiety is a high-profile non-platinum catalyst toward the oxygen reduction reaction (ORR), but its unsatisfactory activity and inadequate stability hinder the practical application. Herein, a novel strategy by hybridizing FePc with fullerene-derived intrinsic defect-rich carbon to improve its ORR activity and stability is reported. Via alkali-assisted thermal pyrolysis, C60 molecules are disintegrated into tiny fragments that then restructure into pentagon- and edge-rich carbon (FC). Utilizing FC as a support of FePc leads to a significantly improved ORR activity compared to other supports including reduced graphene oxide and carbon nanotube that hold distinct structural features. The optimized FePc/FC with a Fe loading of 3 wt% presents a half-wave potential of 0.917 V, far beyond that of Pt/C (0.846 V), via selective four-electron ORR pathway and excellent stability under accelerated stress test. The practical applicability of FePc/FC is also demonstrated as a high-performing cathode catalyst of aqueous zinc-air batteries. It is, for the first time, explicitly disclosed that strong interactions between FePc molecules and intrinsic carbon defects (e.g., pentagons and edges) not only strengthen the anchoring effect of supported FePc but also enhance the intrinsic ORR activity of single-atom Fe-N4 sites. An intrinsic defect-rich carbon derived from the thermal disintegration of fullerene (C60) is utilized as a novel support for iron phthalocyanine molecules. Due to the favorable interaction between intrinsic defects and Fe-N4 moieties, significantly enhanced catalytic activity and stability, far beyond that of commercial Pt/C, are observed toward alkaline oxygen reduction reaction.image (c) 2024 WILEY-VCH GmbH