Potential-dependent Pt(111)—water interface: Tackling the challenge of a consistent treatment of electrochemical interfaces

The interface between an electrode and an electrolyte is the location where electro- chemical processes for countless technologically important applications occur. Though its high relevance and the intense efforts devoted to its elucidation, an atomic-level description of the interfacial structure and especially the dynamics of the electric double layer is still amiss. Here, we present reactive force field molecular dynamics simulations of electrified Pt(111)|water interfaces, shedding light on the orientation of water molecules in the vicinity of the Pt(111) surface, considering the influence of potential, adsorbates and ions simultaneously. We obtain a shift of the water’s preferred orientation in the surface oxidation potential region, breaking with the so far proclaimed strict correlation to the free charge density. Further, the course of the entropy and the intermolecular ordering in the interfacial region complements the characterization. Our work contributes to the ongoing understanding process of electric double layers and in particular of the structure of the electrified Pt(111)|water interface and aims at providing insights into electrochemical processes occurring there.