Beyond Dielectrics: Interfacial Water Orientational Polarization Governs Graphene-Based Electrochemical Interfaces

Abstract

Water molecules are traditionally viewed as passive dielectric media in electrochemical systems. In this work, we challenge this conventional perspective through molecular dynamics simulations and theoretical analysis. We demonstrate that interfacial water exhibits a distinct orientational polarization compared to bulk water and excessively screens the electrostatic potential between ions and the surface, going beyond the classic electric double layer (EDL) model, which considered water merely a passive dielectric. This overscreening occurs because a significant portion of water polarization responds directly to the graphene surface in addition to screening the electrostatic interaction betw..