In situ structural study on underpotential deposition of Ag on Au(111) electrode using surface X-ray scattering technique

In situ surface X-ray scattering (SXS) measurements were carried out to study the structure of a Ag layer on a Au(111) electrode formed by underpotential deposition (upd) in sulfuric acid solution. Specular rod profiles showed that a monolayer of Ag was formed at a potential between the second and third upd peaks, and a bilayer of Ag was formed at a potential between the third upd peak and bulk deposition. Non-specular rod profiles demonstrated that electrochemically deposited Ag atoms both in the first and second layers were situated at the threefold hollow cubic closest packing (ccp) site of the underlying Au and Ag layers, respectively.