Ligand‐Directed Nitrate Incorporation Into Reconstructed Oxyhydroxides for Durable Seawater Electrolysis

ABSTRACT Chloride ions (Cl − )‐induced corrosion severely limits the practical implementation of direct seawater electrolysis. Although oxyanion incorporation can mitigate Cl − poisoning, existing approaches offer limited control over oxyanion generation and retention during catalyst reconstruction. Herein, we report a MOF‐based ligand‐engineering strategy that enables defined oxyanion incorporation into reconstructed metal oxyhydroxides for active and durable seawater electrolysis. Nitro‐ (NO 2 ) functionalized ligands are incorporated into a NiFe‐MOF precursor, where the NO 2 group undergo a simple and direct oxidation to nitrate (NO 3 − ) during electrochemical reconstruction, enabling well‐defined NO 3 − regulation of the reconstructed γ‐NiFeOOH phase. The anchored NO 3 − not only forms a robust Cl − ‐repelling interface but also activates lattice oxygen to drive a mechanistic transition from an adsorbate evolution mechanism to a more efficient lattice‐oxygen‐mediated pathway. The designed catalyst achieves excellent oxygen evolution reaction performance in alkaline seawater, requiring an overpotential of only 230 mV to reach a current density of 500 mA cm −2 , outperforming its NO 3 − ‐free counterpart. It also exhibits high durability, operating for over 4000 h at 1.5 A cm −2 with an ultralow degradation rate of 1.8 µV h −1 . Furthermore, a kilowatt‐level alkaline seawater electrolyzer equipped with the designed electrode operates stably for over 1100 h under industrially relevant conditions.