In Situ Reconstructed Corrosion‐Resistant PO x y ⁻ Prolongs Electrode Lifespans for Efficient Ampere‐Level Water/Seawater Oxidation

Economical, stable, and corrosion‐resistant catalytic electrodes are still urgently needed for the oxygen evolution reaction (OER) in water and seawater. Herein, a mild electroless plating strategy is used to achieve large‐scale preparation of the “integrated” phosphorus‐based precatalyst (FeP–NiP) on nickel foam (NF), which is in situ reconstructed into a highly active and corrosion‐resistant (Fe)NiOOH phase for OER. The interaction between phosphate anions (PO x y − ) and iron ions (Fe 3+ ) tunes the electronic structure of the catalytic phase to further enhance OER kinetics. The integrated FeP–NiP@NF electrode exhibits low overpotentials for OER in alkaline water/seawater, requiring only 275/289, 320/336, and 349/358 mV to reach 0.1, 0.5, and 1.0 A cm − 2 , respectively. The in situ reconstructed PO x y − anion electrostatically repels Cl − in seawater electrolytes, allowing stable operation for over 7 days at 1.0 A cm − 2 in extreme electrolytes (1.0 M KOH + seawater and 6.0 M KOH + seawater), demonstrating industrial‐level stability. This study overcomes the complex synthesis limitations of P‐based materials through innovative material design, opening new avenues for electrochemical energy conversion.