ABSTRACT Ionic liquids (ILs) are promising electrotunable lubricants due to their unique molten salt properties. Here, we elucidate how surface curvature modulates the electrotunability of friction at single‐asperity contacts lubricated by 1‐ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide. Single‐layer graphene (SLG) with nanoscale curvatures was prepared by coating graphene onto SiO 2 nanoparticles (NPs) of varying diameters (10, 20, and 30 nm), supported on a flat, oxidized Si wafer. Friction tests performed by atomic force microscopy (AFM) showed that SLG on 10 nm NPs significantly enhanced the electrotunability of friction compared to SLG on larger NPs and flat graphene. Molecular dynamic simulations revealed changes in ionic rearrangement with varying surface potential. Correlating frictional response with interfacial ionic structure reveals a two‐fold mechanism: when the curvature approaches the nanoscale comparable to ion size, reduced steric interactions arise, improving friction electrotunability. These findings demonstrate how nanoscale surface geometry at electrified interfaces can be exploited to control friction, advancing IL‐based lubrication in micro‐ and nanoelectromechanical systems.
Song et al. (Sat,) studied this question.