title: Structure and dynamics of the interface between a Ag single crystal electrode and an aqueous electrolyte.
abstract: The aim of this work is to elucidate the initial steps of the electrochemical oxidation of Ag(111) in alkaline electrolytes. We use electrochemical as well as ex situ (XPS) and in situ (SHG) spectroscopic techniques to reconstruct the Ag(111)/electrolyte interface as a complex dynamic entity. Moving in the direction from negative to positive potentials we first observe specific adsorption of hydroxide ions, which starts at ca. -1.1 V vs. Ag/Ag2O in 0.1 M NaOH. SHG data prove that hydroxide retains its negative charge. At -0.3 V oxidation of the surface sets in with the formation of negatively charged adsorbed oxygen species and Ag+ ions, which give rise to peaks at 528.2 +/- 0.2 eV and at 367.7 eV in the O 1s and the Ag 3d(5/2) XP spectra, respectively. Around -0.1 V the adlayer is transformed into an ordered surface oxide phase which grows via a nucleation and growth mechanism. Above the reversible Ag/Ag2O potential the 2D Ag(I) oxide transforms into a 3D Ag(I) oxide. The electrochemical oxidation is compared with the previously studied gas-phase process, demonstrating both remarkable similarities as well as some differences.
authors.affiliation: Boreskov Institute of Catalysis, Russian Academy of Sciences, Novosibirsk. savinova@ph.tum.de
authors.forename: Elena R
authors.initials: ER
authors.lastname: Savinova
authors.forename: Andreas
authors.initials: A
authors.lastname: Scheybal
authors.forename: Matthias
authors.initials: M
authors.lastname: Danckwerts
authors.forename: Ute
authors.initials: U
authors.lastname: Wild
authors.forename: Bruno
authors.initials: B
authors.lastname: Pettinger
authors.forename: Karl
authors.initials: K
authors.lastname: Doblhofer
authors.forename: Robert
authors.initials: R
authors.lastname: Schlögl
authors.forename: Gerhard
authors.initials: G
authors.lastname: Ertl