The Electrified Oil/Water Interface in the Presence of Divalent Ions

Experimental advances in X-rays scattering have made possible to measure the distribution of ions near oil-water interfaces in the presence of applied electric fields with atomic precision. However, the interpretation of such experimental data depends strongly on a reliable representation of the ionic cloud or electrical double layer close to these liquid interfaces. In this work, simulations and theory are used to study the electrical properties of the interface between two immiscible electrolytes in the presence of divalent ions, when both solvents are confined by a pair of charged electrodes. Ion correlations, ionic excluded volume effects, image charges, and solvation energies are included in the simulations to quantify the relevance of these effects beyond widely used classical mean-field theories. Electrochemical experimental data are also used to evaluate the performance of these theoretical approaches.