Water Density in the Double Layer

Abstract

A recently proposed approach to the problem of ion hydration in solutions is extended to water at a charged metallic electrode. Water in the closest proximity of the electrode is compressed due to electrostriction and the dipole moments of H2O molecules become completely ordered by extremely strong electric field created by the surface charge. It is estimated that for common values of the charge density of the order of 10-1 C m-2 the effect of striction corresponds to that of pressures of the order of gigapascals. A consistency between the present approach and recent X-ray measurements of the density of water at a silver electrode is discussed.