Editing open metal sites for unlocking industrial-level seawater electrolysis

Seawater electrolysis is a sustainable route to hydrogen, but chloride-induced corrosion of oxygen evolution anodes remains a major obstacle.1 Although intercalation or coating strategies can block Cl- adsorption, they often impede reaction kinetics by introducing inert components.2 Here, by designing secondary linkers in metal-organic frameworks (MOFs), we create open metal sites that selectively and kinetically favor the adsorption of hydroxide ion (OH-) over chloride (Cl-), thereby suppressing corrosion. Guided by machine learning, we construct DHTPxHTP1-x-MOF-74 with Ni0.8Fe0.2 nodes using optimal linker pair 2,5-dihydroxyterephthalic acid (DHTP) and 2-hydroxyterephthalic acid (HTP). Complementary analysis using X-ray total scattering-based pair distribution function and X-ray absorption spectroscopy confirms successful and precise editing of Ni open sites while preserving MOF integrity by introducing secondary HTP. This design yields record performance: DHTP0.8HTP0.2-MOF-74 achieves 3 A cm-2 at 1.75 V in an alkaline seawater electrolyzer (60°C) and operates stably for >3,100 hours at 1 A cm-2 (25°C). Moreover, it sustains 1,000-hour durability at 400 mA cm-2 in an industrial electrolyzer stack at 80°C.