Adsorption on metal electrodes: principles

Abstract

Whenever the concentration of a species at the interface is greater than can be accounted for by electrostatic interactions, we speak of specific adsorption . It is usually caused by chemical interactions between the adsorbate and the electrode, and is then denoted as chemisorption . In some cases adsorption is caused by weaker interactions such as van der Waals forces; we then speak of physisorption . Of course, the solvent is always present at the interface; so the interaction of a species with the electrode has to be greater than that of the solvent if it is to be adsorbed on the electrode surface. Adsorption involves at least a partial desolvation. Cations tend to have a firmer solvation sheath than anions, and are therefore less likely to be adsorbed.