Evolution of Interfacial Hydration Structure Induced by Ion Condensation and Correlation Effects

作者：Han Li, Zhi Ping Xu, Jiacheng Li, Alessandro Siria, Ming Ma · 发表于：Angewandte Chemie International Edition · 年份：2024 · DOI：10.1002/anie.202418029 · 被引用次数：12 · 研究领域：Electrostatics and Colloid Interactions、Spectroscopy and Quantum Chemical Studies、Lipid Membrane Structure and Behavior

Abstract Interfacial hydration structures are crucial in wide‐ranging applications, including battery, colloid, lubrication. Multivalent ions like Mg 2+ and La 3+ show irreplaceable roles in these applications, which are hypothesized due to their unique interfacial hydration structures. However, this hypothesis lacks experimental supports. Here, we provide the first observation for their interfacial hydration structures with molecular resolution using atomic force microscopy. We observed the evolution of layered hydration structures at La(NO 3 ) 3 solution‐mica interfaces. As concentration increases from 25 mM to 2 M, the layer number varies from 2 to 1 and back to 2, and the interlayer thickness rises from 0.25±0.05 to 0.34±0.03 nm, with hydration force increasing from 0.27±0.07 to 1.04±0.24 nN. Theory and molecular simulation reveal that the cations form inner‐sphere complexes. Multivalence induces concentration‐dependent ion condensation and correlation effects, resulting in compositional and structural evolution within interfacial hydration structures. Additional experiments at seven different solid–liquid interfaces together with literature comparison confirm the universality of this mechanism for both multivalent and monovalent ions. New factors affecting interfacial hydration structures are revealed, including concentration and solvent dielectric constant. This insight provides guidance for designing interfacial hydration structures to optimize solid–liquid‐interphase ...