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Titolo:
In situ STM study of electrodeposition and anodic dissolution of Ni on Ag(111)
Autore:
Lachenwitzer, A; Morin, S; Magnussen, OM; Behm, RJ;
Indirizzi:
Univ Ulm, Abt Oberflachenchem & Katalyse, D-89069 Ulm, Germany Univ Ulm Ulm Germany D-89069 lachenchem & Katalyse, D-89069 Ulm, Germany
Titolo Testata:
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
fascicolo: 16, volume: 3, anno: 2001,
pagine: 3351 - 3363
SICI:
1463-9076(2001)3:16<3351:ISSSOE>2.0.ZU;2-#
Fonte:
ISI
Lingua:
ENG
Soggetto:
SCANNING-TUNNELING-MICROSCOPY; NICKEL ELECTRODEPOSITION; BORIC-ACID; VITREOUS CARBON; ELECTROCHEMICAL DEPOSITION; RECONSTRUCTED AU(111); COPPER DEPOSITION; ISLAND NUCLEATION; PLACE-EXCHANGE; INITIAL-STAGES;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
78
Recensione:
Indirizzi per estratti:
Indirizzo: Lachenwitzer, A Univ Guelph, Dept Chem & Biochem, Guelph, ON N1G 2W1, Canada Univ Guelph Guelph ON Canada N1G 2W1 , ON N1G 2W1, Canada
Citazione:
A. Lachenwitzer et al., "In situ STM study of electrodeposition and anodic dissolution of Ni on Ag(111)", PHYS CHEM P, 3(16), 2001, pp. 3351-3363

Abstract

A study of the electrodeposition and electrochemical dissolution of ultrathin Ni films on Ag(111) electrodes in Watts electrolyte by in situ scanningtunneling microscopy (STM), electrochemical quartz microbalance (EQCM), and cyclic voltammetry (CV) is presented. Ni deposition starts at potentials negative of -0.72 V vs. SCE (i.e., overpotentials eta greater than or equalto 160 mV), where an incommensurate, (111)-oriented film with an in-plane lattice rotation of 0.5 degrees relative to the Ag substrate lattice is formed. The lateral nearest neighbor spacing is as in bulk Ni (2.49 Angstrom) for a film thickness greater than or equal to 3 ML and expanded for monolayer (2.54 Angstrom) and bilayer (2.52 Angstrom) films. Depending on the deposition potential, three growth regimes, resulting in different deposit morphologies, are observed: At low overpotentials (160 less than or equal to eta /mV less than or equal to 200) a smooth Ni film is formed via a 2D step-flow growth process, commencing at steps of the Ag substrate. At medium overpotentials (200 greater than or equal to eta /mV greater than or equal to 300) a transformation from 2D step-flow to 3D growth occurs, resulting in the selective formation of Ni multilayer islands along the Ag steps. At even higher overpotentials (eta greater than or equal to 300 mV) 3D islands are formed at the steps and on the substrate terraces. The size of the Ni multilayer islands is independent of the terrace widths, indicating that Ni growth proceeds via direct discharge at step sites ("direct deposition"). The transition from 2D to 3D growth as well as the change in island shape with overpotential can be rationalized by a different potential dependence of thevarious microscopic nucleation and growth processes. The multilayer growthat steps is attributed to next-layer nucleation at the structural defect induced by the Ag-Ni boundary and can be described quantitatively as a function of deposition time by a simple 2D model. In addition, place-exchange ofNi with Ag surface atoms and encapsulation of Ni islands by Ag is observed. Dissolution of the electrodeposited multilayer Ni films proceeds via step-flow etching, with a higher dissolution rate for the Ni monolayer as compared to higher Ni layers.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 26/09/20 alle ore 12:02:30