Blocking Effect Retards Electron Release from Asymmetric Active Units for Selective Seawater Oxidation

During seawater electrolysis, chloride ion (Cl^–) adsorption at the anode leads to an inevitable competitive chloride oxidation reaction (ClOR) with the oxygen evolution reaction (OER), compromising the long-term stability of the electrolysis process. Furthermore, Ni-based OER electrocatalysts are challenged by activity degradation due to the overoxidation of Ni³⁺. In response, we present a design of oxygen-vacancy-regulated asymmetric Nb–O–Ni bonds aimed at selective seawater oxidation. The experimental and in situ characterization results indicate that the blocking effect of oxygen vacancies effectively alleviates the electron release of Ni³⁺ and the electron enrichment of Nb⁵⁺ on asymmetric Nb–O–Ni bonds, achieving a stable and selective OER in alkaline seawater. Density functional theory (DFT) calculations reveal that oxygen vacancies in Nb–O–Ni bonds optimize the adsorption strength of reaction intermediates and break up the scaling relationship between *OH and *OOH intermediates. The constructed anion exchange membrane electrolysis cell achieves a cost efficiency of $1.07 per GGE (gasoline gallon equivalent) for H₂ production at a current density of 1000 mA cm^–2, maintaining operational stability for 100 h at 500 mA cm^–2.