Ultrafast 60‐Second Synthesis of Meter‐Scale Ni‐based Catalysts via Phosphomolybdic Acid Complexation for Durable Seawater Oxidation at 1 A cm ⁻²

Direct seawater electrolysis offers a sustainable pathway for hydrogen production, yet the development of cost‐effective catalysts with high activity, durability, and scalable preparation remains challenging. Here, we report a mild interfacial synergistic etching strategy that enables the rapid fabrication of efficient oxygen evolution catalysts. Nickel foam is controllably etched by phosphomolybdic acid (PMA) and trace Fe 3 + , yielding meter‐scale catalysts (60‐Fe‐PMA/NF) within 60 s at room temperature. The synergistic incorporation of iron and the dynamic leaching–reabsorption of phosphomolybdate in alkaline media promote rapid surface reconstruction, enhancing chloride corrosion resistance and impurity tolerance. As a result, 60‐Fe‐PMA/NF exhibits superior stability under harsh seawater electrolysis conditions. In a zero‐gap electrolyzer, it operates steadily for more than 270 h at 1.0 A cm −2 in alkaline seawater (1 M KOH + seawater). This work demonstrates a scalable, low‐cost strategy for constructing robust OER catalysts, advancing practical seawater electrolysis toward sustainable hydrogen production.