ADSORPTION OF ORGANIC-SUBSTANCES AT ELECTRODES - RECENT ADVANCES

Recent developments concerning four areas in the field of adsorption of organic compounds at electrodes are critically examined and discussed. The topics are: (1) possibility of experimental determination of the molecular size factor, n; (2) effect of the nature of the metal on the Gibbs energy of adsorption; (3) effect of the crystallographic orientation of the metal surface; (4) effect of functional groups in the adsorption of aromatic compounds from non-aqueous solvents. Results show: (1) the value of n appears to be congruent-to 1 for all substances irrespective of the molecular size; (2) the nature of the metal is mainly seen through the desorption of the preadsorbed water molecules; (3) the effect of the atomic density of the metal surface cannot be assessed unambiguously from the few data available; (4) functional groups can change the adsorbate-solvent interactions as well as the aromaticity of the benzene ring. The combined effects can turn a physical interaction with the metal surface into a strong, specific chemical interaction via the pi-electron system, as a consequence of changes in the interfacial orientation.