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 SO₄^2-, 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.