Sulfur-Induced Asymmetric Ni-Fe Dual Single-Atom Sites for Decoupling Electrocatalytic Oxygen Activation From...

The practical deployment of seawater-based zinc-air batteries (SZABs) is critically hindered by the dual challenges of sluggish oxygen reduction reaction (ORR) kinetics and severe chloride-induced deactivation of conventional catalysts. Herein, we report an asymmetric Ni─Fe dual single-atom catalyst, denoted as NiFe-SNC, featuring atomically adjacent NiN₄ and FeN₃S moieties. This unique architecture enables synergistic side-on O₂ adsorption across dual-metal sites, facilitating direct O─O bond cleavage via a dissociative four-electron ORR pathway. Crucially, first-shell sulfur coordination on the Fe center modulates its electronic structure, effectively reducing its Lewis acidity and thereby suppressing competitive Cl^- adsorption. In situ spectroscopic studies and theoretical calculations jointly validate this decoupled mechanism, where high ORR activity and exceptional chloride tolerance are achieved simultaneously. Consequently, NiFe-SNC delivers a record-high half-wave potential (E_1/2) of 0.932 V versus RHE for alkaline seawater ORR. When integrated into SZABs, it achieves a peak power density of 187.74 mW cm^-2 and demonstrates remarkable stability with over 300 h of continuous charge-discharge cycling. This work establishes a precise atomic-level design paradigm, offering a generalizable strategy to engineer robust electrocatalysts that transcend the inherent limitations of seawater electrolytes for next-generation marine energy systems.