THEORY OF THE INTERFACIAL POTENTIAL DISTRIBUTION AND REVERSIBLE VOLTAMMETRIC RESPONSE OF ELECTRODES COATED WITH ELECTROACTIVE MOLECULAR FILMS

An analytical expression for the interfacial potential distribution at metal electrodes coated with monolayer and submonolayer films of electroactive molecules is reported. The driving force for reversible electron transfer between the metal and electroactive adsorbate is calculated from the interfacial potential distribution and is used to predict the current-voltage wave shape in cyclic voltammetric experiments. The shape of the voltammetric wave and the potential at which it is observed are shown to be functions of the thickness and dielectric constant of the adsorbate film, the surface concentration of electroactive adsorbate, the concentration and type of supporting electrolyte, the solvent dielectric constant, and the potential of zero charge (E(PZC)). An analytical expression is also presented for the capacitance of adsorbate-covered electrodes.