Dissociative oxygen reduction on FeCo dual-atom catalysts for enhanced Zn–air battery performance

초록

Single-atom catalysts (SACs) for the oxygen reduction reaction (ORR) are constrained to associative pathways because adsorption-energy scaling makes O–O bond cleavage unfavorable. Dual-atom catalysts (DACs) can overcome this limitation through cooperative interactions, but direct mechanistic evidence is scarce. Here, we demonstrate that FeCo dual-atom sites enable a dissociative pathway. Guided by multi-pathway density functional theory (DFT) calculations, we identify FeCo dual-atom sites as an optimal DAC. The resulting FeCo-N-C catalyst achieves an onset potential of 0.96 V, comparable to Pt/C and higher than SACs under identical conditions. Kinetic analysis and in situ spectroscopy show suppressed *OOH accumulation and a Tafel slope of –82 mV dec–1, distinct from the associative pathway of Fe-N-C (–119 mV dec–1). Grand-canonical DFT calculations reveal that FeCo dual-site cooperativity lowers the *OOH dissociation barrier, providing a mechanistic basis for enhanced activity, while Zn–air battery tests confirm superior performance versus Pt/C, highlighting the practical relevance of the dissociative pathway.

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