Low temperature anomalies in the properties of the electrochemical interface

Some features of the adsorption isotherms and electrochemical capacitance of electrolytes in solvents at low temperatures are studied by means of computer simulations. The so-called restricted primitive model where the ions are represented as charged hard spheres of equal diameter and the solvent is represented by a uniform dielectric constant is used. It is found that at low temperatures the capacitance of double layers in dissolved electrolytes decreases with decreasing temperatures. This is similar to the behaviour of the capacitance of molten salt double layers but opposite to the behaviour of double layers in dissolved electrolytes at room temperature. Further, we find a maximum in the adsorption isotherm near the critical point of the electrolyte. This quantity may well be singular at the critical point.