MOLECULAR-DYNAMICS SIMULATION OF THE ADSORPTION OF BENZENE ON CHARGED METAL-ELECTRODES IN THE PRESENCE OF AQUEOUS-ELECTROLYTE

Classical molecular dynamics was used to model the adsorption of benzene on metal electrodes in a thin electrochemical cell containing aqueous NaCl solution. On uncharged electrodes benzene was adsorbed mostly flat and the ions formed a neutral diffuse region between the electrodes. As the charge on the electrode was increased the diffuse layer rearranged to shield the center of the film from the electric field. The remaining high electric field at the surface caused ordering of water molecules next to the metal, and this in turn promoted benzene desorption. Desorption occurred first from the cathode because of a higher surface electric field between the hydrated sodium ion in solution and the negative electrode. At the anode the field across the water layer was lower because the chloride ion was adsorbed in contact closer to metal than the water layer. At the highest electrode charge density both ions were adsorbed in contact On their respective electrodes and benzene was desorbed from both surfaces into the central aqueous region.