Electrochemical Potential–Driven Ion Migration and Interfacial Adsorption in Ionic Liquids

Although electrical energy storage and microfluidic systems employing electrically responsive ionic media such as ionic liquids (ILs) have seen substantial progress, the mechanisms by which ion migration and adsorption at electrochemically controlled interfaces dictate wettability and triboelectric behavior remain elusive. In this work, we investigated the interfacial adsorption and friction behaviors of two ILs containing imidazolyl chains and imidazolylamino cations on charged, organosilicon-modified Au surfaces. The mechanisms of ion migration and adsorption were further elucidated through molecular dynamics simulations. Notably, the two ILs exhibited opposite friction responses under negative electrical potentials, revealing an ion-specific electro-responsive behavior. This difference arises from the interplay of van der Waals attractions, electrostatic interactions, and short-range forces, which collectively govern wetting strength and dominate the dissipation of sliding energy. Furthermore, a semi-quantitative correlation between nanofriction and ILs wettability under applied potentials was established, highlighting the critical role of molecular structure design in enabling tunable electro-responsive friction. By identifying key molecular and interfacial parameters that control electro-responsive friction, this work provides strategies for optimizing surface functionalization, ionic liquid selection, and applied potentials in electro-lubrication systems, while establishing molecular-level design rules for electrically tunable interfaces with broad implications for micro/nanofluidics, electrowetting, soft robotics, and energy-storage applications.