Electrochemical deposition of copper onto Pt(111) in the presence of (bi)sulfate anions

Using in situ x-ray diffraction we have studied the underpotential deposition (UPD) of copper onto a Pt(111) electrode in sulfuric acid. Deposition occurs in a two-stage process; close to a full monolayer of Cu being preceded by a $(\sqrt{3}\times \sqrt{3})R30\mathrm{}°$ structure that consists of both Cu and (bi)sulfate anions and is similar to the structure observed on the Au(111) electrode. Utilizing anomalous scattering methods we can accurately determine the Cu coverage during UPD and propose structural models based on crystal truncation rod measurements.