Chloride‐resistant seawater electrolysis via hydroxyl network‐tailored <scp>NiFe</scp> hydroxide catalysts on stainless steel

Abstract Hydrogen production via seawater electrolysis is limited by chloride corrosion and slow oxygen evolution reaction (OER) kinetics. Here, we present hydroxyl network‐engineered NiFe hydroxide catalysts on stainless steel (SS‐NiFe‐X) via a rapid one‐step electrodeposition strategy. During OER, the NiFe hydroxide layer transforms into an active NiFeOOH/NiOOH phase, while in situ ‐generated surface hydroxyl networks establish hydrogen‐bond‐mediated pathways that simultaneously enhance OER activity and shield against chloride attack. SS‐NiFe‐60, with a 500 nm oxide layer, sustains 400 mA cm −2 for over 500 h in an aggressive chloride environment (1.0 M KOH + 2.0 M NaCl), while the bare SS experiences complete deactivation within 1 h. Operando studies reveal that the hydroxyl network could block chloride penetration by electrostatic repulsion and facilitate OER intermediate adsorption, validated by a membrane electrode assembly electrolyzer stably delivering 250 mA cm −2 for over 100 h. This scalable design bridges mechanistic insights with industrial seawater electrolysis applications.