Enhanced Stability and Catalytic Performance of Iron–Manganese Dual-Atoms Supported on Graphene Edges for Oxygen Reduction Reaction

This computational study explores the structural stability and catalytic performance of FeMn-based dual-atom catalysts (DACs) embedded in graphitic materials, focusing on active sites located at graphene edges. Using density functional theory (DFT) calculations and microkinetic simulations, we show that graphitic edges, particularly armchair edges, effectively stabilize the ortho-configured FeMnN6 active site. This configuration demonstrates enhanced catalytic performance for the oxygen reduction reaction (ORR) compared to FeMnN6 sites at zigzag edges or on basal graphene. In contrast, initial para-configured FeMnN6 and MnFeN6 active sites exhibit limited ORR activity due to OH- or O-poisoning. Interestingly, the presence of adsorbed *OH and *O intermediates not only stabilizes the system but also improves catalytic efficiency, enabling effective ORR activation. Acid stability calculations further reveal that while the ortho configuration performs well in high-pH environments, the poisoned para configuration offers broader pH tolerance, indicating complementary strengths. Overall, the findings highlight the critical role of edge effects in shaping the stability and functionality of FeMnN6 and MnFeN6 active sites, offering valuable insights for the development of efficient nonprecious metal catalysts for ORR applications.