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Titolo:
In-situ STM investigation of specific anion adsorption on Cu(111)
Autore:
Broekmann, P; Wilms, M; Kruft, M; Stuhlmann, C; Wandelt, K;
Indirizzi:
Univ Bonn, Inst Phys & Theoret Chem, D-53115 Bonn, Germany Univ Bonn Bonn Germany D-53115 hys & Theoret Chem, D-53115 Bonn, Germany
Titolo Testata:
JOURNAL OF ELECTROANALYTICAL CHEMISTRY
fascicolo: 1-2, volume: 467, anno: 1999,
pagine: 307 - 324
Fonte:
ISI
Lingua:
ENG
Soggetto:
SCANNING-TUNNELING-MICROSCOPY; SULFURIC-ACID-SOLUTIONS; ELECTRODE SURFACES; UNDERPOTENTIAL DEPOSITION; ATOMIC-RESOLUTION; AU(111) ELECTRODE; EX-SITU; PT(111); CHLORINE; SULFATE;
Keywords:
in situ STM; adsorption kinetics; copper; sulfate adsorption; chloride adsorption; low index single crystal surfaces; solid vertical bar liquid interfaces; superlattices;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
47
Recensione:
Indirizzi per estratti:
Indirizzo: Broekmann, P Univ Bonn, Inst Phys & Theoret Chem, Wegelerstr 12, D-53115 Bonn, Germany Univ Bonn Wegelerstr 12 Bonn Germany D-53115 5 Bonn, Germany
Citazione:
P. Broekmann et al., "In-situ STM investigation of specific anion adsorption on Cu(111)", J ELEC CHEM, 467(1-2), 1999, pp. 307-324

Abstract

The specific anion adsorption of chloride and sulfate on Cu(111) from acidic aqueous electrolytes has been studied using scanning tunneling microscopy (STM) and cyclic voltammetry. At positive potentials adsorbed chloride forms a well ordered (root 3 x root 3)R30 degrees superstructure; at negativepotentials the bare copper surface can be imaged with atomic resolution. By use of a so-called potentiodynamic STM measurement it is possible to correlate directly the appearance and the disappearance of the chloride superstructure to the anodic and the cathodic peak in the cyclic voltammogram. Thechloride adsorbate influences the surface topography strongly in such a way that copper steps preferentially run along close packed chloride rows after chloride adsorption. An enhanced surface mobility caused by the chlorideadsorbate leads to an 'electrochemical annealing' effect. Surface defects such as pits heal rapidly and the decay of copper stacks is promoted. Although the cyclic voltammograms of Cu(111) in chloride acid electrolyte and insulfuric acid electrolyte are similar, both showing characteristic adsorption and desorption peaks, the surface structures and the adsorption kinetics are extremely different. At positive potentials the sulfate adsorbate forms an anisotropic Moire structure which occurs in three rotational domains. High resolution STM images reveal an additional species which is assigned to coadsorbed water molecules. Close packed sulfate rows are separated by zig-zag chains of these water molecules. The short range lattice vectors of the sulfate structure are similar to those found for sulfate adlayers on other fcc(111) surfaces (Au, Pt, Rh). Due to a strong kinetic hindrance it ispossible to observe directly the mechanism of the sulfate adlayer formation and the decay process. The Moire formation starts locally at upper step edges and spreads from the step edges over the upper terraces. During the adlayer formation process a mass transport out of the top copper layer takes place, resulting in a drastic change of the surface topography due to the formation of characteristically shaped islands and step edges. Different models are discussed explaining the long range periodicity of the Moire pattern and the topographic changes during the adlayer formation and decay processes. (C) 1999 Elsevier Science S.A. All rights reserved.

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Documento generato il 04/06/20 alle ore 01:50:26