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

Fe-N-C catalysts with single-atom Fe-N₄ 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-N₄ catalysts. The integration of Fe-N₄ configurations with highly uniform Co₄ ACs on the N-doped carbon substrate (Co₄ @/Fe₁ @NC) is realized through a "pre-constrained" strategy using Co₄ molecular clusters and Fe(acac)₃ implanted carbon precursors. The as-developed Co₄ @/Fe₁ @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 H₂ -O₂ fuel cell test. First-principles calculations further clarify the ORR catalytic mechanism on the identified Fe-N₄ that modified with Co₄ ACs. This work provides a viable strategy for precisely establishing atomically dispersed polymetallic centers catalysts for efficient energy-related catalysis.