Self-protecting Fe@NiAl electrocatalyst mediated by aluminate ions enables durable alkaline seawater oxidation

Electrochemical seawater splitting is typically hindered by the corrosive effect of chloride ions (Cl⁻) on catalytic active sites during the oxygen evolution reaction (OER). Herein, a self-protecting Fe@NiAl electrocatalyst mediated by aluminate ions (Al(OH) 4 ⁻) was synthesized via a novel in-situ etching-oxidation strategy, which acts as an efficient and durable OER catalyst in alkaline seawater electrolyte. Comprehensive characterization techniques reveal that the incorporation of FeOOH and generation of oxygen vacancies (O vac ) modulate the chemical composition and electronic structure of Fe@NiAl, thereby promoting a γ-NiOOH/γ-FeOOH synergistic effect to enhance the OER activity. Of particular importance, the in-situ-generated Al(OH) 4 ⁻ within the Fe@NiAl catalyst exert a strong repulsive effect toward Cl⁻ in seawater, thereby significantly enhancing the catalyst’s corrosion resistance. Density functional theory (DFT) calculations demonstrate that FeOOH incorporation lowers the energy barrier for the formation of OER active intermediates, while Al(OH) 4 ⁻ generation reduces the Cl⁻ adsorption energy. A flow-type anion exchange membrane (AEM) electrolyzer utilizing Fe@NiAl as the bifunctional electrode achieves a cell voltage of merely 2.31 V at 1.0 A cm⁻ 2 and sustains stable operation for 800 h in alkaline seawater. This work provides valuable insights and a feasible strategy for designing robust and corrosion-resistant electrocatalysts for industrial-scale seawater electrolysis applications.