Iron and oxygen vacancies co-modulated adsorption evolution and lattice oxygen dual-path mechanism for enhanced ampere-level freshwater/seawater oxidation

Conjointly activating metal and lattice oxygen sites to trigger the adsorbate evolution and lattice oxygen mechanisms coupled path holds promise for balancing activity and stability in oxygen evolution reaction (OER) catalysts, yet confronting significant challenges. Herein, we develop Fe species and oxygen vacancies co-regulated Ni-(oxy)hydroxide (O_V-Ni(Fe)OOH), derived from deep reconstruction of Fe-Ni₂P/NiMoO₄ pre-catalyst during OER, which realizes the AEM-LOM dual-path mechanism with optimal metal-oxygen covalent bonds, as confirmed via in-situ mass/spectroscopy spectrometry and chemical probes. Experimental details and theoretical calculation analysis reveals the enhanced AEM kinetics on the Ni site via the co-regulation of Fe species and O_V, featuring upshifted Ni 3d band centers, while the Fe incorporation activates the O site with preferable adsorption free energy for LOM intermediates. Benefiting from the AEM-LOM dual-path mechanism, the activated Fe-Ni₂P/NiMoO₄ catalyst affords an ampere-scale current density of 1.0 A cm^{− 2} at low overpotentials of 275 and 299 mV in 1 M KOH and 1 M KOH + seawater, respectively, and maintains seawater electrocatalysis for 480 h in the anion exchange membrane water electrolysis (AEMWE) cell. This work demonstrates a strategy to trigger the dual-path OER mechanism for efficient and stable electrocatalytic water splitting under harsh conditions.