Precisely manipulated π–π stacking of catalytic exfoliated iron polyphthalocyanine/reduced graphene oxide hybrid via pyrolysis-free path.

The precisely manipulated π–π stacking of the hybrid catalyst favors the specific prediction of the ORR active sites, which are the iron atoms in the form of natural Fe-N 4 that bind preferentially to the oxygen. [Display omitted] Metal macrocycles with well-defined molecular structures are ideal platforms for the in-depth study of electrochemical oxygen reduction reaction (ORR). Structural integrity of metal macrocycles is vital but remain challenging since the commonly used high-temperature pyrolysis would cause severe structure damage and unidentifiable active sites. Herein, we propose a pyrolysis-free strategy to precisely manipulate the exfoliated 2D iron polyphthalocyanine (FePPc) anchored on reduced graphene oxide (rGO) via π–π stacking using facile high-energy ball milling. A delocalized electron shift caused by π–π interaction is firstly found to be the mechanism of facilitating the remarkable ORR activity of this hybrid catalyst. The optimal FePPc@rGO-HE achieves superior half-wave potential (0.90 V) than 20 % Pt/C. This study offers a new insight in designing stable and high-performance metal macrocycle catalysts with well-defined active sites. [ABSTRACT FROM AUTHOR]