Dual‐Pathway Chloride Suppression Enables Stable Industrial‐Scale Anion Exchange Membrane Seawater Electrolysis

ABSTRACT Suppressing anodic chlorine evolution while enhancing hydrogen production in seawater electrolysis requires simultaneous regulation of the Cl − adsorption behavior and inhibition of its kinetic migration. However, integrated strategies to mitigate the associated corrosive effects remain underexplored. Herein, we demonstrate a dual‐pathway strategy, where the Fe‐SO x δ− bonding and the formation of SO x δ− anion‐rich layers synergistically provide effective protection for SO x δ− ‐Ni 3 S 4 @NiFe‐MOF/NF catalysts in seawater environments. Experimental and theoretical studies reveal that partial SO x δ− chemically coordinates with Fe sites, altering the local electronic structure and increasing the Cl − adsorption energy. Simultaneously, uncoordinated SO x δ− leaches into the electrolyte and spontaneously forms the surface anion‐rich layers via polarization effect, hampering the kinetic migration of Cl − . Benefiting from this dual protection, the catalyst achieves a low overpotential of 350 mV at 1.5 A cm −2 and superior stability over 600 h with a small decay rate of 0.93 µV h −1 in alkaline seawater. The assembled seawater electrolyzer presents a small cell voltage (1.74 V @ 1 A cm −2 ), high‐energy conversion efficiency (75.6%), and lower H 2 production cost ($0.88 per GGE) than the target set by the U.S. Department of Energy. The proposed dual‐pathway regulation strategy offers a new paradigm for the design of high‐performance chloride‐resistant catalysts.