Influence of anion adsorption on the step dynamics on Au (111) electrodes

Using scanning tunneling microscopy, we have investigated the step dynamics on an Au(111) single crystal electrode in aqueous electrolytes. Our studies focused on the influence of specifically adsorbed anions and the anion concentration on the mobility of gold atoms at monatomic-high step edges. The experiments were performed in chloride-containing and chloride-free H2SO4 electrolytes. From the quantitative analysis of equilibrium step fluctuations we deduce the dominant mass transport mechanisms as a function of the electrode potential and as a function of the anion concentration. Estimates of the energies involved in the mass transport are presented.