Influence of the adsorption of organic compounds on submonoleyer stripping voltammetry of metals at solid electrodes

The effect of the adsorption of foreign organic compounds on the stripping voltammetry of metal adatoms deposited in submonolayer amounts at solid electrodes has been analyzed. It is shown that, for irreversible metal deposition processes, the adatom deposition current and, at a constant deposition time, the deposition charge are sensitive to the presence of the adsorbed foreign species on the electrode surface. Equations describing the dependence of the metal adatom deposition charge and the stripping peak current on the deposition potential, deposition time, concentration, and lateral exchange interactions between metal adatoms and adsorbed molecules have been derived. In the case of negligible exchange interactions, the peak current for adatom probe desorption decreases linearly with the surface coverage by foreign adsorbate. Direct evaluation of the kind and strength of exchange interactions is possible because the expression derived for the metal adatom desorption peak potential was used. It was found that the shift of the peak potential to more positive potentials is due to the lateral attraction exchange interactions, while the shift to more negative potentials was caused by the exchange repulsion interactions. No shift in the peak potential occurred in the absence of exchange interactions irrespective of the adatom surface coverage after the deposition step.