CuO@NiCoS NAs Heterostructure Boosting Anionic Ligand Defect Sites Enabled 2000 h Stable Seawater Electrolysis

Abstract Seawater electrolysis cooperates well with renewable energy sources at arid coastal photovoltaic power parks and maritime mobile wind farms, thus minimizing hydrogen production expenditure. However, the deleterious electrochemistry of aggressive chloride ions proceeding in two‐electron processes reveals a kinetic preponderance compared to the sluggish four‐electron seawater oxygen evolution reaction (OER), restricting the efficiency and durability of seawater electrolyzers. In this work, the decoration of low electronegativity Cu 2+/1+ cation substituents is proposed to trigger the dual‐site lattice oxygen mechanism (LOM), which can involve both the metal sites and anionic ligand defect sites to participate in seawater OER. Theoretical and experimental investigations indicate the modified band structure and electron interaction of the CuO@NiCoS NAs heterostructure, thus inducing the defect center formation and optimizing the anodic electrochemistry during seawater electrolysis. The operando electrochemistry techniques unveil the promoted anodic activation and LOM catalysis enabled by the inductive effect of Cu─O groups, which corresponds to the inhibited chloride corrosion and facilitated seawater oxidation. Hence, the non‐noble metal‐based electrolyzer consisting of CuO@NiCoS NAs/NF (anode) || NiCoS NAs/NF (cathode) exhibits a promising durability during the alkaline seawater electrolysis, exceeding 2000 h at an industrial‐scale current density of 1.0 A cm −2 .