TY - JOUR A1 - Bier, Markus A1 - Mußotter, Maximilian A1 - Dietrich, S. T1 - Structure of electrolyte solutions at nonuniformly charged surfaces on a variety of length scales JF - Physical Review E N2 - The structures of dilute electrolyte solutions close to nonuniformly charged planar substrates are systematically studied within the entire spectrum of microscopic to macroscopic length scales by means of a unified classical density functional theory approach. This is in contrast to previous investigations, which are applicable either to short or to long length scales. It turns out that interactions with microscopic ranges, e.g., due to the hard cores of the fluid molecules and ions, have a negligible influence on the formation of nonuniform lateral structures of the electrolyte solutions. This partly justifies the Debye-Hückel approximation schemes applied in previous studies of that system. In general, a coupling between the lateral and the normal fluid structures leads to the phenomenology that, upon increasing the distance from the substrate, fewer details of the lateral nonuniformities contribute to the fluid structure, such that ultimately only large-scale surface features remain relevant. It can be expected that this picture also applies to other fluids characterized by several length scales. KW - Classical statistical mechanics, Electrostatic interactions, Interface & surface thermodynamics, Complex fluids, Ionic fluids, Liquid-solid interfaces, Polymers & Soft Matter, Statistical Physics Y1 - 2022 UR - https://doi.org/10.1103/PhysRevE.106.054801 VL - 106 IS - 5 SP - 054801 ER - TY - JOUR A1 - Mußotter, Maximilian A1 - Bier, Markus A1 - Dietrich, S. T1 - Heterogeneous surface charge confining an electrolyte solution JF - The Journal of Chemical Physics N2 - The structure of dilute electrolyte solutions close to a surface carrying a spatially inhomogeneous surface charge distribution is investigated by means of classical density functional theory within the approach of fundamental measure theory. For electrolyte solutions, the influence of these inhomogeneities is particularly strong because the corresponding characteristic length scale is the Debye length, which is large compared to molecular sizes. Here, a fully three-dimensional investigation is performed, which accounts explicitly for the solvent particles, and thus provides insight into effects caused by ion–solvent coupling. The present study introduces a versatile framework to analyze a broad range of types of surface charge heterogeneities even beyond the linear response regime. This reveals a sensitive dependence of the number density profiles of the fluid components and of the electrostatic potential on the magnitude of the charge as well as on the details of the surface charge patterns at small scales. KW - Density functional theory, Fundamental measure theory, Electrostatics, Partial differential equations, Elementary particle interactions, Electrochemistry, Electrolytes, Interfaces Y1 - 2020 UR - https://doi.org/10.1063/5.0006208 VL - 152 IS - 23 ER -