The Adsorption of Aromatic Hydrocarbons at the Gold Electrolyte Interface

Abstract

The potential and concentration dependent adsorption of benzene, naphthalene, and phenanthrene at the gold/electrolyte interface has been investigated using a 14C-radio tracer technique. For a fixed concentration of organic material the adsorption peak was found at about +500 my (NHE) and the potentialadsorption curve was bell shaped, adsorption decreasing with potential on either side of the peak. An analysis of the adsorption isotherms for naphthalene leads to the conclusion that naphthalene lies fiat on the electrode surface. Comparison of the extent of adsorption of the aromatic hydrocarbons with cyclohexane, n-octanoic acid, and n-decanoic acid (no detectable adsorption) indicates that aromatic compounds have a higher binding energy with metals than the corresponding aliphatic compounds. The added binding energy for aromatic molecules is attributed to their π-electron systems. Finally a comparison of mercury with gold points to the stronger binding energy of water to gold than to mercury. © 1963, The Electrochemical Society, Inc. All rights reserved.