Activating Lattice Oxygen via Enhanced Ni–O Covalency for Robust Industrial-Level Seawater Electrolysis

Achieving efficient and stable seawater electrolysis remains a significant challenge. Herein, an FeMo–Ni(OH) 2 catalyst is fabricated through hierarchical ion doping combined with electrochemical oxidation activation, enabling highly efficient and durable oxygen evolution reaction (OER) for alkaline seawater electrolysis at industrial-level current densities. Fe doping modifies the active centers, driving a mechanistic transition from the adsorbate evolution mechanism to the lattice oxygen oxidation mechanism. Concurrently, Mo doping enhances the Ni–O covalency by modulating the electron density around the Ni atoms, thereby boosting both the stability and intrinsic activity of the FeMo–Ni(OH) 2 catalyst. Furthermore, the electrochemical activation process induces the formation of SO 4 2–, which generates a protective layer on the anode surface that repels Cl – . This effectively suppresses competitive chloride oxidation reactions and mitigates anode corrosion, resulting in an OER selectivity of over 80%. Consequently, the FeMo–Ni(OH) 2 catalyst achieves low overpotentials of 322 mV at 1000 mA cm –2 in alkaline seawater and 290 mV at 1000 mA cm –2 in 1 M KOH, alongside exceptional operational stability exceeding 1000 h, outperforming most reported OER catalysts. This work provides valuable insights into achieving a synergistic balance between the OER activity and stability for practical seawater electrolysis.