DFT-based modeling of cation–water interactions and dynamics in nanopores

The interaction of alkali-exchanged montmorillonite surfaces with cations was systematically examined using density functional theory (DFT) to evaluate how alkali metal ions (Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺) influence surface energy. These interactions were analyzed and contrasted with those involving alkaline earth cations (Mg²⁺, Ca²⁺, Ba²⁺) to elucidate the impact of ionic charge and radius on the clay framework's energetics. To gain insight into ion transport phenomena at the clay surface, we introduced a minimalist hopping model that captures cation migration between energetically favorable sites. Complementary impedance spectroscopy measurements during controlled water adsorption provided experimental validation, revealing that hydration markedly lowers migration energy barriers and modifies surface energetics. This integrated computational–experimental approach advances our understanding of ion mobility in hydrated aluminosilicates and underscores the central role of water in shaping interfacial ionic dynamics.