The initial stages of rhodium deposition on Au(111)

Abstract

Abstract The electrochemical deposition of rhodium on Au(111) was studied by means of in-situ STM and cyclic voltammetry. A phase transition within the [RhCl6]3− adlayer was found for Au(111) in 0.1 M H2SO4+10−4 M RhCl3+10−3 M HCl at 520 mV versus SCE, where a ( 13 × 13 )R13.9°-superstructure of [RhCl6]3− is formed on the gold substrate. Rhodium starts to deposit irreversibly around 200 mV versus SCE. First a rhodium bilayer grows, the electrochemical behaviour of which is similar to that of a well-ordered Rh(111) surface. On top of the second rhodium monolayer the formation of small, three-dimensional clusters is observed. The electrocatalytic properties of rhodium films with an average thickness up to ten monolayers were studied by using CO oxidation as a test reaction. The influence of the surface structure on the CO oxidation kinetics is discussed briefly.