Enhanced diffusion of surface atoms at metal/electrolyte interface under potential control

We have investigated the surface self-diffusion coefficient (D(s)) on Ag(100) in aqueous 50 mM H(2)SO(4) solution using electrochemical atomic force microscopy (ECAFM). The results were compared with those observed on Au(100). The D(s) values of Ag(100) increased exponentially with potential between -50 and 350 mV (vs. normal hydrogen electrode, NHE). From the D(s)-E relationship, we propose that the activation energy of surface diffusion decreases because of the surface excess charge. We also found that the D(s) values on Ag(100) were a hundred times larger than those on Au(100) within the potential range from 150 to 350 mV (vs. NHE). (C) 1998 Elsevier Science B.V. All rights reserved.