The surface diffusion of Au atoms in 0.5M H2SO4 at 298K was deduced from the time dependence of the surface roughness factor of electro-dispersed 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