Revealing the Synergistic Enhancement Effect of Dual Metal RuFe(Co) Sites for Bifunctional Oxygen Catalysis

Modifying the geometric and electronic structures of metal-N-C single-atom catalysts to improve their catalytic activities is quite desirable and challenging. Here, theoretical analysis and experi-ment indicate the inherent synergistic effect of dual metal sites in N-doped carbon for bifunctional ORR and OER. Specifically, introducing Ru to generate RuFe-N-C or RuCo-N-C double-atom catalysts (DACs) can significantly enhance the bifunctional ORR/OER activities of Fe(Co) and Ru sites, exceeding the equivalent single metal Fe(Co)- N-C and Ru-N-C. Investigations of a series of RuM-N-C DACs reveal that the intriguing synergistic effect results from the modified charge density and d-band center by combining two optimized metal atoms, which affects adsorption energies of intermediates and catalytic activity. Based on these theoretical guidelines, RuFe-N-C is synthesized using a bimetal MOF as the precursor, and it exhibits exceptional ORR/ OER activities in alkaline media with a small Delta E of 0.63 V, significantly outperforming Fe-N-C, Ru-N-C, and even commercial Pt/C-RuO2.