Functional Bimetal Co‐Modification for Boosting Large‐Current‐Density Seawater Electrolysis by Inhibiting Adsorption of Chloride Ions

Abstract Designing efficient and durable electrocatalysts for seawater splitting to avoid undesired chlorine evolution reaction and resist the corrosive seawater is crucial for seawater electrolysis technology. Herein, a functional bimetal (Co and Fe) is designed specifically to modify nickel phosphide (denoted as CoFe‐Ni 2 P) for boosting seawater splitting, where the Fe atom improves the conductivity of Ni 2 P for improving electron transfer, and the Co atom accelerates the self‐reconstruction process to favorably generate bimetal co‐incorporated NiOOH (CoFe‐NiOOH) species on the electrode surface. Additionally, these in situ‐generated CoFe‐NiOOH species remarkably inhibit the adsorption of Cl − ions but selectively adsorb OH − ions, which contributes to excellent performance of the CoFe‐Ni 2 P electrode for large‐current‐density seawater splitting. Therefore, the CoFe‐Ni 2 P electrode only requires low overpotentials of 266 and 304 mV to afford current densities of 100 and 500 mA cm −2 in a harsh 6 m KOH + seawater electrolyte, and can work stably for 600 h. Impressively, a flow‐type anion exchange membrane electrolyzer assembled by the CoFe‐Ni 2 P/Ni‐felt bifunctional electrode is demonstrated to run stably at an industrially large current density of 1.0 A cm −2 in 6 m KOH + seawater electrolyte for 350 h, which shows promising application prospects.