Electrochemistry of sub-monolayer silver deposits on single crystal RuO 2 (110), (001) and (111) electrodes

Abstract

Asymmetric stripping peaks for sub-monolayer Ag films deposited on RuO 2 single crystal electrodes have been observed for (110) and (001) surfaces where both Ru and O sites are available on the ideal surface. Interpretation of this observation in terms of irreversible and quasi-reversible adsorption of silver leads to an interaction coefficient g close to −4 which may result in the formation of Ag islands (new phase) due to the strong attractive lateral forces. On the other hand, a symmetric Ag stripping peak is characteristic for the RuO 2 (111) surface where only Ru sites are available on the ideal surface. This indicates a reversible adsorption process for which the value of g was determined to be −1. The weaker lateral attraction forces seem to be associated with the different geometrical arrangement of Ag adatoms on different crystallographic faces of the RuO 2 single crystals rather than with increased substrate-adatom interactions since no major shifts in the peak potential were observed.