This study explores how FeNi embedded nitrogen-doped graphene enhance oxygen reduction efficiency, outperforming single-metal catalysts. By combining density functional theory and mechanistic analysis, it is revealed that FeNi synergy optimizes electron transfer and intermediate stabilization, enabling faster reaction kinetics and lower energy barriers. The design offers a blueprint for high- performance catalysts in fuel cells.

Developing highly effective single-atom catalysts for oxygen reduction reaction (ORR) is critical to improve fuel cell efficiency. Hence, this study systematically investigates ORR performance of single-metal (FeN₄-G, NiN₄-G) and dual-metal (FeNiN₃-G) catalysts embedded in nitrogen-doped graphene through density functional theory (DFT) calculations. Through analysis of ORR intermediates adsorption on M-N-C surfaces, the Gibbs free energy changes, density of states, and electron transfer profiles of catalytic systems are investigated. DFT calculations reveal that while the over-binding of FeN₄-G and intermediates impedes desorption kinetics and weak interactions of NiN₄-G favor the less efficient 2e⁻ pathway, FeNiN₃-G addresses these limitations through synergistic Fe-Ni electronic coupling. By optimizing d-band alignment and charge redistribution, FeNiN₃-G lowers the rate-determining step energy barrier and reduces overpotential. Moreover, the dual-metal configuration promotes selective 4e⁻ ORR via efficient OO bond cleavage. This work provides mechanistic insights for designing high-efficiency M-N-C electrocatalysts for energy conversion technologies.