Xianbiao Hou, Zhaozheng Zhang, Jian Zhou, Tengjia Ni, Canhui Zhang, Shuixing Dai, Lei Chu, Hao Wang, Heqing Jiang, Minghua Huang
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.