In situ STM study of the initial stages of electrochemical oxide formation at the Ag(1 1 1)/0.1 M NaOH(aq) interface

• Published in: Electrochemistry communications Vol. 6; no. 2; pp. 132 - 137
• Main Authors: Kunze, Julia, Strehblow, Hans-Henning, Staikov, Georgi
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01.02.2004; Amsterdam Elsevier Science; New York, NY
• Subjects: Adsorption; Chemistry; Electrochemical oxide formation; Electrochemistry; Exact sciences and technology; General and physical chemistry; Silver; Solid/liquid interface; STM; Study of interfaces; Electrochemical oxide formation; Silver; Solid/liquid interface; Adsorption; STM; Alkali metal Compounds; Electrode adsorption; Electrode electrolyte interface; Transition metal; Crystal face; Surface topography; Experimental study; Sodium hydroxide; Surface structure; Scanning tunneling microscopy; Surface reconstruction; Crystal electrode
• ISSN: 1388-2481; 1873-1902
• DOI: 10.1016/j.elecom.2003.10.027

The atomic structure of surface layers and the local changes of surface morphology during the initial stages of anodic oxidation of Ag(1 1 1) in an aqueous 0.1 M NaOH solution have been investigated by in situ scanning tunneling microscopy (STM) under different polarization conditions. The surface oxide formation starts at underpotentials, i.e. at electrode potentials E below the Nernst-potential E 3 D Ag 2 O ( vs. SHE )=0.4 V for the formation of the three-dimensional (3D) bulk Ag 2O phase. An ordered overlayer showing distinct Moiré pattern is observed in the potential range −0.1 V<E (vs. SHE) <0.1 V. The appearance of the Moiré structure is assigned to the strong OH adsorption, which induces a stretching of the 2D lattice of the OH-terminated topmost Ag(1 1 1) monolayer. In situ STM imaging at higher potentials (0.1 V < E (vs. SHE) <0.3 V) shows the occurrence of a Ag dissolution process followed by an underpotential oxide formation in agreement with previous electrochemical measurements and in situ X-ray absorption studies.