Fe‐Free Mn‐Modulated Co Single‐Atom Catalysts for Highly Durable Oxygen Reduction Reaction in Proton Exchange Membrane Fuel Cells

ABSTRACT Discovering non‐noble metal catalysts that can circumvent traditional activity‐stability trade‐off is critical for the development of proton exchange membrane fuel cells (PEMFCs). Incorporating two distinct MNx single‐atom sites into carbon catalysts is emerging as an effective strategy to simultaneously boost activity and stability for oxygen reduction reaction (ORR). Herein, we construct cobalt‐manganese dual‐metal single‐atom catalysts (Co,Mn‐SACs‐CNF) with abundant MnNx sites and CoNx sites anchored on N‐doped carbon frameworks. Detailed characterization studies confirm the co‐existence of isolated Co and Mn atoms in the catalysts. Density functional theory calculations establish that Co single atoms act as the active center during ORR for oxygen adsorption and reduction, whilst Mn single atoms serve as electron donors to regulate the electronic structure of Co sites, thus optimizing the d‐band position of Co sites and favorably tuning the binding energy of oxygen intermediates. Benefitting from the synergistic interaction between nearby Co and Mn atoms, the synthesized Co,Mn‐SACs‐CNF exhibits outstanding stability after 10,000 cycles in 0.5 M H2SO4, whilst delivering comparable ORR activity to the state‐of‐the‐art Pt/C. The stability enhancement is further demonstrated in PEMFC tests, with the device showing a modest (19.6%) loss in initial peak power density after a 30,000‐cycle accelerated stress test.