Construction of Co₄ Atomic Clusters to Enable Fe-N₄ Motifs with Highly Active and Durable Oxygen Reduction Performance

Fe-N-C catalysts with single-atom Fe-N-4 configurations are highly needed owing to the high activity for oxygen reduction reaction (ORR). However, the limited intrinsic activity and dissatisfactory durability have significantly restrained the practical application of proton-exchange membrane fuel cells (PEMFCs). Here, we demonstrate that constructing adjacent metal atomic clusters (ACs) is effective in boosting the ORR performance and stability of Fe-N-4 catalysts. The integration of Fe-N-4 configurations with highly uniform Co-4 ACs on the N-doped carbon substrate (Co-4@/Fe-1@NC) is realized through a "pre-constrained" strategy using Co-4 molecular clusters and Fe(acac)(3) implanted carbon precursors. The as-developed Co-4@/Fe-1@NC catalyst exhibits excellent ORR activity with a half-wave potential (E-1/2) of 0.835 V vs. RHE in acidic media and a high peak power density of 840 mW cm(-2) in a H-2-O-2 fuel cell test. First-principles calculations further clarify the ORR catalytic mechanism on the identified Fe-N-4 that modified with Co-4 ACs. This work provides a viable strategy for precisely establishing atomically dispersed polymetallic centers catalysts for efficient energy-related catalysis.