Chemo-mechano-structural interplay in fully hydrated ion clusters on hexagonal boron nitride nanosheet surfaces

Abstract

The theoretical understanding of the coupling relationship between ionic thermodynamics and electron kinetics in the vicinity of fluid–solid interfaces is highly important. In this study, the chemo–mechano–structural interplay of the hydrated ion cluster that governs the equilibrium state in adsorption is elucidated using all-atom model computations. Specifically, the physicochemical properties of four (sodium, chloride, hydronium, and ammonium) fully hydrated ions in bulk solution and on the surface of a hexagonal boron nitride nanosheet (hBNNS) substrate were comparatively investigated. The results suggest that the intrinsic structure and charged state of these ions are key in determining the internal structure—symmetry, water ligand alignment, and hydrogen-bonded network structure—of the hydrated ion clusters. The shape of the hydrated ion cluster has a significant impact on the mechanical behavior during inner-sphere adsorption of the ion. Furthermore, the electron kinetics of the hydrated ion–hBNNS interface are strongly dependent on the arrangement of the water ligands and water network inside the ion cluster. This study is the first to elucidate the coupled mechanism of multiple hydrated ion clusters, providing new insights into the molecular scale understanding of electrical double-layer electrode, desalination separator, and proton transport membrane systems in practical engineering.