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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]

Bifunctional catalyst was prepared by one-step pyrolysis of trimetallic ZIF. The obtained catalyst showed excellent charge–discharge stability in rechargeable Zn-air battery. • A facile and effect strategy is proposed for the synthesis of catalyst precursor. • This strategy reduces the adverse effects of the pyrolysis process on the catalyst. • The coexistence of Co NPs and CoFe-N x improves the ORR/OER activity. • The catalyst displays excellent durability as a cathode for Zn-air battery. Searching for high active, low cost and durable catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) remains challenge in developing metal-air battery cathodes. Herein, we proposed a novel bifunctional catalyst derived from the pyrolysis of Co/Fe/Zn trimetallic zeolitic imidazolite framework. The obtained Co@CoFe 0.01 N C catalyst displays desirable activity for both ORR and OER (E 1/2 = 0.844 V, E j=10 = 1.654 V). The Zn-air battery equipped with Co@CoFe 0.01 N C catalyst on the cathode exhibits a high peak power density of 174.1 mW cm−2, which is much superior than that of commercial 20% Pt/C (87.6 mW cm−2). Significantly, the designed Co@CoFe 0.01 N C presents an outstanding stability for over 100 h in rechargeable Zn-air battery. [ABSTRACT FROM AUTHOR]