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Register a new userHeterogeneous surface charge confining an electrolyte solution
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Added by
Maximilian Mu{\\ss}otter
Publication date
2020
fields
Physics
and research's language is
English
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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.
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Electrical conductivity is an inherent property of a hydrophobic porous media (HPM) and has critical applications. This research aims to provide a solution for predicting the electrical conductivity of nanoscale HPM with heterogeneous pore structure. Molecular dynamics (MD) simulations are compared with the modified Poisson-Boltzmann (MPB) model for understanding ionic charge density distributions in nanopores. The effective medium approximation (EMA) participates in calculating the effective conductance and conductivity of the nanoscale HPM. The results show that the surface charge density affects the ionic density profiles in the hydrophobic nanopores. As the pore size increases, the conductance increases. As the molarity of the aqueous electrolyte solution (AES) decreases, the conductance decreases. A phenomenon related to the conductance saturation occurred when the molarity of AES is very low. The effective conductance of an HPM increase as the coordination number increases. Finally, based on the calculated effective conductance and the heterogeneous pore structure parameters, the electrical conductivity of a nanoscale HPM is calculated.
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