Accelerating Catalyst Reconstruction via Silver Sulfide Doping: A Dual‐Anion Shielding Strategy for Robust Seawater Electrolysis

Abstract The slow electrochemical reconstruction of conventional nickel‐based catalysts in alkaline seawater electrolysis creates a critical vulnerability window, leading to irreversible chloride corrosion before a protective oxyhydroxide phase can form. Overcoming this kinetic barrier is paramount for developing durable anodes. In this study, an Ag doping and surface sulfurization strategy that directly confronts this challenge by enabling the ultrafast reconstruction of a NiCo‐based hydroxide catalyst (Ag ₂ S‐NiCo(OH) _x ) is introduced. This process is complete in ≈2.2 h, effectively closing the window for corrosion and rapidly establishing a robust, active phase. The fully reconstructed catalyst exhibits exceptional performance, delivering an industrial current density of 500 mA cm ⁻² at an overpotential of 357 mV in alkaline simulated seawater. Its remarkable durability, evidenced by stable operation for over 110 h at 500 A cm ⁻² , is attributed to a novel dual‐barrier protection mechanism. Abundant oxygen vacancies, induced during the rapid activation, serve to anchor in situ generated SO ₄ ²⁻ anions. These anions, in synergy with an enriched surface OH ⁻ layer, create a powerful electrostatic shield that repels chloride ions. This work demonstrates that kinetically accelerating catalyst reconstruction is a powerful strategy to bypass intrinsic material vulnerabilities, offering a new paradigm for designing robust catalysts for practical seawater oxidation.