(400i) Large Modification of Electrostatic Fields in Liquids Between Charged Plates: Effects of the Dielectric Response of Solvent Molecules

We study the effects of dielectric inhomogeneity on the electrostatic properties of liquids between two charged plates, developing a modified Poisson-Boltzmann equation via the Booth theory for the dielectric response of solvents under external electrostatic fields. We show that variations in the capacitance for ion-containing solutions can be non-monotonic, whereas the conventional Poisson-Boltzmann theory predicts monotonic behavior. Importantly, the effects of ions on the reorganization of solvent dipoles near electrodes significantly affect the capacitance. We also illustrate that hydrogen bonding can be critically important to optimize the capacitance that non-monotonically varies with the charge densities on electrodes. Furthermore, we show that the dielectric contrast in immiscible liquid mixtures may cause conceptually new phase behaviors between charged plates; interfaces between the liquids perpendicular to an external field may be energetically favored over parallel interfaces.