A Conductive and Ion‐Selective Electrocatalyst Enables Stable and Efficient Direct Saline Water Splitting

ABSTRACT Seawater electrolysis is promising for green hydrogen production, while its application is inhibited by sluggish anodic oxygen evolution reaction (OER) and rapid chloride corrosion‐induced electrode deactivation. Herein, we report a conductive and ion‐selective OER electrocatalyst with a CoFe alloy core and microporous metal‐doped carbon shell. Co/Fe‐N ₄ ‐C active sites in the shell optimize the adsorption strength of intermediates and synergize with the metal core to endow the catalyst with high OER activity and selectivity, while the rich ultra‐micropores in the shell demonstrate a significant sieving effect to hinder Cl ⁻ transfer, thus protecting the inner Co/Fe‐N ₄ ‐C active sites and metal core from Cl ⁻ corrosion. The catalyst is assembled in an alkaline seawater electrolyzer with an electrode geometric area of 254 cm ² and delivers a current density of 3000 A m ⁻² at 1.85 V for 330 h. Such catalysts can be synthesized in a large batch (100 g), providing sound opportunities for industrial seawater splitting.