Molecular dynamics simulation of adsorption in electric double layers

Abstract

Classical molecular dynamics is used to model the structure and dynamics of electric double layers that form when a metal electrode is in contact with an aqueous electrolyte solution containing simple ions and neutral organics. First attention is focused on the distribution of ions and neutrals next to an uncharged electrode. The electric field and potential across the system are calculated. The iodide ion adsorbs from neutral solution and causes a negative shift in the potential of zero charge (PZC) relative to fluoride. Adsorbed benzene causes a small positive shift of the PZC. Benzene desorbs when the metal electrode is charged and the surface electric field causes a layer of localized and oriented water to form next to the electrode. Non contact adsorbed hydrated sodium ions are more effective than contact adsorbed chloride in desorbing benzene.