Acetate adsorption on Pt(111): Implications for copper underpotential deposition and surface oxidation

Acetate stabilizes the Cu underpotential deposition (UPD) on Pt(111) as shown previously for Cu UPD on Au(111). A similar kinetic hindrance of Cu bulk deposition (OPD) for Pt(111) and Au(111) is found. The adsorption of acetate therefore leads to a broad potential window for a stable Cu UPD monolayer. Pt(111) surface oxidation shows a strong kinetic hindrance in the presence of acetate. The processes of Cu UPD and surface oxidation are dependent on the previous Cu deposition for Pt(111). This effect is attributed to the competitive adsorption of hydroxide and acetate. A model for Cu UPD on different Pt(111) surface sites is developed to describe variations of the charges of the two Cu UPD peaks governed by dissimilar anion adlayers. The extent of Pt(111) surface oxidation can be controlled by a specific Cu UPD routine.