layer are a major drawback to their cost-effective commercialization. To date, although platinum-group metal-based catalysts have been recognized as the best-performing ORR electrocatalysts, their future use as cathode catalysts is limited by scarcity and high costs, meaning that alternative economic cathode catalysts are greatly needed. [1] Among tremendous research efforts toward developing non-precious electrocatalysts, transition-metal-based metal-N4 (MN4) macrocyclic compounds have emerged as promising non-platinum group metal electrocatalysts after the pioneering breakthrough of Jasinski in 1964, who reported a cobalt phthalocyaninebased electrocatalyst. [2] Recent studies have reported a broad range of macrocyclic MN4 centers, such as Co and Fecoordinated porphyrins, phthalocyanines, corrins, and corroles, that possess promising non-precious metal active catalytic sites for the ORR. [2][3][4][5] A common feature of these macrocyclic MN4 systems is a single transition metal atom with biomimetic ligands, and with the maintenance of these single-metal-atom MN4 active sites as electrocatalysts being the most important factor in improving the ORR. Therefore, the use of these N4 macrocyclic complexes for developing A heterobimetallic corrole complex, comprising oxygen reduction reaction (ORR) active non-precious metals Co and Fe with a corrole-N4 center (PhFCC), is successfully synthesized and used to prepare a dual-atom molecular catalyst (DAMC) through subsequent low-temperature pyrolysis. This low-temperature pyrolyzed electrocatalyst exhibited impressive ORR performance, with onset potentials of 0.86 and 0.94 V, and half-wave potentials of 0.75 and 0.85 V, under acidic and basic conditions, respectively. During potential cycling, this DAMC displayed half-wave potential losses of only 25 and 5 mV under acidic and alkaline conditions after 3000 cycles, respectively, demonstrating its excellent stability. Single-cell Nafion-based proton exchange membrane fuel cell performance using this DAMC as the cathode catalyst showed a maximum power density of 225 mW cm −2 , almost close to that of most metal-N4 macrocycle-based catalysts. The present study showed that preservation of the defined CoN4 structure along with the cocatalytic Fe-Cx site synergistically acted as a dual ORR active center to boost overall ORR performance. The development of DAMC from a heterobimetallic CoN4macrocyclic system using low-temperature pyrolysis is also advantageous for practical applications.

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