STM imaging of noble metal electrodes in solution under potentiostatic control

Abstract

We have combined a three-electrode cell arrangement with a scanning tunnelling microscope (STM) to image the surfaces of polycrystalline noble metal electrodes under potentiostatic conditions. STM imaging was made in the potential range where a tip and the electrodes are ideally polarized. We have observed on a submicron scale that the electrochemically roughened Ag electrode surface relaxed over times of 40 min at -0-16 V versus SCE in 0.1 M KCl. We have also imaged a dynamic process (formation and dissociation) of the submicron-scale reconstruction of the Au electrode subjected to electrochemical oxidation-reduction cycles. The results can be explained by the absorption of C1-ions and the surface diffusion of adatoms or clusters. STM imaging under potentiostatic control leads to the discovery of phenomena occurring at solid metal/electrolyte interfaces.