  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 (DFT) within the approach of fundamental
measure theory (FMT). 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 details of the surface
charge patterns at small scales.
