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

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- (NO₂) functionalized ligands are incorporated into a NiFe-MOF precursor, where the NO₂ group undergo a simple and direct oxidation to nitrate (NO₃ ^-) during electrochemical reconstruction, enabling well-defined NO₃ ^- regulation of the reconstructed γ-NiFeOOH phase. The anchored NO₃ ^- 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 NO₃ ^--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.