Tailoring Oxygen Vacancy-Rich NiFe-LDH to Realize Seawater Oxidation with a High Efficiency and Selectivity

In the context of seawater electrolysis, the inevitable adsorption of chloride ions (Cl–) at the anode surface induces a concurrent competitive oxidation reaction (ClOR), which subsequently decreases the prolonged operational stability of the electrolytic system. Here, nickel iron hydroxide supported on nickel foam with rich oxygen vacancies (Ov-NiFe(OH)X) has been synthesized by a fast and simple electrodeposition combined with the impregnation method. Ov can synergistically modulate the electronic structure of NiFe-based hydroxides to realize the electronic redistribution and induce rapid phase reconstruction, and the activated Ni phase with a higher valence acts as a Lewis acid center, which can endow Ov-NiFe(OH)X with high OH– selectivity and Cl– repulsion in seawater, thus realizing the selective and efficient oxidation of seawater. The Ov-NiFe(OH)X anode-equipped seawater AEM electrolyzer exhibits an exceptional performance, characterized by remarkable activity (1.78 V at 500 mA cm–2) and sustained operational durability (120 h of continuous operation at 500 mA cm–2). Notably, the AEM achieves an operational efficiency of 74.0% under 200 mA cm–2 when tested in a 1.0 M KOH/seawater electrolyte mixture, corresponding to a cost-effective hydrogen production cost of $0.9 per GGE.