Cl--driven pathway switching enables efficient industrial-current seawater oxidation on dual-atom catalysts

초록

Direct electrolysis of seawater for hydrogen production offers a vital route to circumvent freshwater limitations and advance a sustainable hydrogen economy. Herein, we present a novel catalyst design strategy based on the co-doping of Ru atoms with strong chloride affinity and Cr atoms serving as Lewis acid centers into a nickel phosphide matrix (RuCr-Ni3P). This material is a highly active anode for direct alkaline seawater electrolysis, offering outstanding oxygen evolution reaction (OER) selectivity and operational longevity exceeding 4000 h under industrially relevant conditions. Mechanistic investigations reveal that chloride ions are not merely detrimental impurities, but are selectively captured by Ru sites to form a dynamic Ru-Cl coordination motif. This interaction electronically modulates adjacent Ni active centers, facilitating the generation of high-valent Ni>3+ species and switching the dominant OER pathway from the lattice oxygen mechanism (LOM) to the more efficient adsorbate evolution mechanism (AEM). Simultaneously, Cr sites promote the formation of Cr-OH species, which cooperatively create a localized alkaline microenvironment favorable for OER on the high-valent Ni centers. This dual-site synergistic mechanism, wherein Ru sites regulate chloride and Ni/Cr sites drive catalysis, effectively transforms Cl- from a performance-limiting species into a chemical switch that concurrently enhances both activity and stability.

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