Rational Coordination Engineering of Fe–Co Dual-Atom Catalysts for Enhanced Oxygen Reduction Reaction via Synergistic Electronic Modulation

The development of efficient dual-atom catalysts (DACs) requires an atomic-level understanding on the microscopic coordination environment that is hard to characterize experimentally. Herein we rationally design DACs with diverse Fe–Co/N₃O₃ configurations, among which the NN_FeOO_CoNO-coordinated configuration is identified to exhibit superior stability and oxygen reduction reaction (ORR) catalytic activity based on first-principles calculations. Mechanistic analysis reveals that the ORR is triggered by side-on adsorption of O₂ on the Co site, enabled by strong hybridization between Co 3d_xz/yz orbitals and O₂ π* antibonding states. The high-spin Fe²⁺ acts as an electron reservoir by transferring charge to Co and lowering its d-band center. The Fe–Co synergy suppresses excessive *OH binding (ΔG₄ = +0.107 eV in Fe-free Co@NO₃) and positions the system to the ORR volcano apex. In summary, synergistic catalysis could be unlocked by rational coordination environmental design combined with spin-state-modulated charge redistribution.