ADSORPTION OF AU-CONTAINING SPECIES AND HETEROGENEOUS ISOTOPE-EXCHANGE OF AU ATOMS AT THE AU ELECTRODE-VERTICAL-BAR-DICYANOAURATE SOLUTION INTERFACE

Both the adsorption of Au-containing species on a polycrystalline gold electrode in alkaline 10(-4) M dicyanoaurate solution and the heterog eneous isotope exchange of Au atoms in this system were studied by the use of 'electrode lowering' radiotracer techniques and Au-195-labelle d dicyanoaurate. At an electrode potential of 0.1 V (SHE), the rate of adsorption of Au-containing species is considerably higher than that of heterogeneous isotope exchange which makes it possible to discrimin ate the contribution of adsorption from that of heterogeneous isotope exchange. The surface concentration of Au-containing species adsorbed on the gold electrode at 0.1 V determined in this study is close to th at of CN-containing species adsorbed in the same system obtained previ ously [1]. The results obtained suggest strongly that AuCN species are adsorbed on a gold electrode from alkaline dicyanoaurate solutions an d the heterogeneous isotope exchange is confined to the atomic monolay er of gold. The rate of heterogeneous isotope exchange at 0.1 V is som e orders of magnitude higher than the partial cathodic current density extrapolated to this potential. (C) 1998 Elsevier Science S.A. All ri ghts reserved.