Ex situ X-ray photoelectron spectroscopy study of the interface between a Ag(111) electrode and an alkaline electrolyte. 1. Influence of the electrode potential on the adsorption of oxygen species

A Ag(111) single-crystal electrode emersed from the NaF + NaOH electrolyte (pH 11) under the anodic polarization has been studied ex situ by means of X-ray photoelectron spectroscopy. The oxidation of the electrode starts at -0.6 V vs Hg/HgO (ca. 1 V negative to the reversible potential of Ag2O phas e formation) and manifests itself by the appearance of different surface an d bulk oxygen-containing species. These are surface OH groups (OHads), surf ace oxide-like species (O-ads(delta-)), and bulk OH groups (OHbulk). The OH bulk exhibit high thermal stability in a vacuum but can be efficiently remo ved from the electrode via cathodic polarization.