The surface diffusion of Au atoms in 0.5M H2SO4 at 298K was deduced from the time dependence of the surface roughness factor of electrodispersed Au electrodes in 0.5M H2SO4. The value of surface diffusivity for 0.5M H2SO4 was 5 x 10-14cm2/s. This figure depended markedly upon the presence of adsorbable species in solution. Thus, the adsorption of pyridine produced a sharp decrease in surface diffusivity, whereas the adsorption of Cl- ions resulted in the reverse effect. The corresponding values of surface diffusivity were 1.2 x 10-14cm2/s for 0.5M H2SO4 plus 0.1M pyridine, and 2.5 x 10-13cm2/s for 0.5M H2SO4 plus 0.0005M KCl. The results were explained in terms of an effect of the adsorbate upon the Au surface atom diffusion mechanism.

C.Alonso, R.C.Salvarezza, J.M.Vara, A.J.Arvia: Electrochimica Acta, 1990, 35[9], 1331-6