Non-planar Nest-like [Fe₂ S₂ ] Cluster Sites for Efficient Oxygen Reduction Catalysis

Metal-nitrogen-carbon catalysts, as promising alternative to platinum-based catalysts for oxygen reduction reaction (ORR), are still highly expected to achieve better performance by modulating the composition and spatial structure of active site. Herein, we constructed the non-planar nest-like [Fe₂ S₂ ] cluster sites in N-doped carbon plane. Adjacent double Fe atoms effectively weaken the O-O bond by forming a peroxide bridge-like adsorption configuration, and the introduction of S atoms breaks the planar coordination of Fe resulting in greater structural deformation tension, lower spin state, and downward shifted Fe d-band center, which together facilitate the release of OH* intermediate. Hence, the non-planar [Fe₂ S₂ ] cluster catalyst, with a half-wave potential of 0.92 V, displays superior ORR activity than that of planar [FeN₄ ] or [Fe₂ N₆ ]. This work provides insights into the co-regulation of atomic composition and spatial configuration for efficient oxygen reduction catalysis.