Hydroxyl Self‐Trapping Strategy Enables Electrocatalysis at Ampere‐Level Current Densities: Kinetics‐Driven Lattice Oxygen Activation for Cl ⁻ ‐Rich Alkaline Water Electrooxidation

ABSTRACT The development of electrocatalysts that both work effectively at industrial current density and resist chloride ion (Cl ⁻ ) corrosion remains a key challenge for hydrogen production from Cl ^‐ ‐rich alkaline water. Herein, we report a CrO _x ‐engineered nickel‐based oxide catalyst (FeCoCrO _x /NF) that achieves exceptional activity and stability through a dual‐functional interfacial mechanism. Combing in situ Raman spectroscopy, ¹⁸ O isotopic labeling, and electrochemical analysis, we demonstrate that the oxygen evolution reaction follows a lattice oxygen‐mediated mechanism. The CrO _x layer selectively adsorbs hydroxide ions, forming a dynamic interfacial barrier that electrostatically repels Cl ⁻ ingress, thereby mitigating Cl ^‐ corrosion. Through enthalpy‐based analysis, we demonstrate that electronic redistribution via Cr–O–Fe bonding increases the vacancy formation energy of Fe, thereby suppressing its dissolution. In alkaline electrolyte containing 0.5 M Cl ⁻ (1.0 M KOH), the catalyst is operating continuously for 1400 h at an industrial current density of 1000 mA cm ⁻² . Furthermore, the catalyst retains 99.5% of its initial activity under fluctuating current density (100–1000 mA cm ⁻² ), demonstrating robustness required for industrial electrolyzers. This study establishes a paradigm for designing corrosion‐resistant electrocatalysts through the synergistic modulation of interfacial ion selectivity and bulk lattice oxygen activation, advancing the application of green hydrogen production in Cl ⁻ ‐rich alkaline water.