Breakdown of Linear Dielectric Theory for the Interaction between Hydrated Ions and Graphene
Philip Loche1, Cihan Ayaz1, Alexander Schlaich1,2
1Fachbereich Physik , Freie Universität Berlin , Arnimallee 14 , 14195 Berlin , Germany.
Abstract:
Many vital processes taking place in electrolytes, such as nanoparticle self-assembly, water purification, and the operation of aqueous supercapacitors, rely on the precise many-body interactions between surfaces and ions in water. Here we study the interaction between a hydrated ion and a charge-neutral graphene layer using atomistic molecular dynamics simulations. For small separations, the ion-graphene repulsion is of nonelectrostatic nature, and for intermediate separations, van der Waals attraction becomes important. Contrary to prevailing theory, we show that nonlinear and tensorial dielectric effects become non-negligible close to surfaces, even for monovalent ions. This breakdown of standard isotropic linear dielectric theory has important consequences for the understanding and modeling of charged objects at surfaces.
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