THE SURFACE-DIFFUSION OF GOLD ATOMS ON GOLD ELECTRODES IN ACID-SOLUTION AND ITS DEPENDENCE ON THE PRESENCE OF FOREIGN ADSORBATES

The surface diffusion coefficient (Ds) of Au atoms in 0.5 M H2SO4 at 298 K has been determined from the time dependence of the surface roughness factor of electrodispersed Au electrodes in 0.5 M H2SO4. The value of Ds for 0.5 M H2SO4 is 5 × 10-14 cm2 s-1, a figure which depends considerably on the presence of adsorbable species in solution. Thus, the adsorption of pyridine produces a remarkable decrease of Ds, Whereas the adsorption of Cl- ion results in the opposite effect. The corresponding values of Ds are 1.2 × 10-14 cm2 s-1 for 0.5 M H2SO4 + 0.1 M pyridine, and 2.5 × 10-13 cm2 s-1 for 0.5 M H2SO4 + 5 × 10-4 M KCl. These results are interpreted through the influence of the adsorbate on the Au surface atom diffusion mechanism. © 1990.