Stimulating the Lewis acidity of Pt–O–Co bridges via vacancy engineering for efficient hydrogen evolution in seawater

Abstract

Seawater electrolysis is considered a promising approach for large scale sustainable hydrogen production. However, its complex ionic environment often causes precipitation formation and Cl⁻ poisoning of active sites, severely hindering the hydrogen evolution reaction (HER) kinetics. Here, we construct a low-Pt-doped and vacancy-rich cobalt oxide catalyst (Pt–CoO_x), in which vacancy rich asymmetric Pt–O–Co bridge structure induces charge polarization and strengthens the Lewis acidity of Co sites, thereby enabling selective OH⁻ adsorption while suppressing chloride ion (Cl⁻) adsorption and effectively preventing poisoning of the Pt active centers. In situ characterization and theoretical calculations reveal that the asymmetric Pt–O–Co bridge with rich O vacancies achieves ideal hydrogen adsorption energetics and disrupts the hydrogen bond network of interfacial water molecules, thereby lowering the energy barrier for water dissociation and preventing the formation of precipitates. Benefiting from above, Pt–CoO_x requires only 160.22 mV to deliver 500 mA cm⁻² in alkaline seawater and maintains excellent durability in natural seawater. When integrated into an anion exchange membrane water electrolyzer (AEMWE), the catalyst achieves an industrial level current density of 1 A cm⁻² at 1.97 V and operates stably for more than 100 hours at 500 mA cm⁻².