Artículo
Surface Structure of 4-Mercaptopyridine on Au(111): A New Dense Phase
Herrera, Santiago Esteban
; Tasca, Federico; Williams, Federico José
; Calvo, Ernesto Julio
; Carro, Pilar; Salvarezza, Roberto Carlos
Fecha de publicación:
09/2017
Editorial:
American Chemical Society
Revista:
Langmuir
ISSN:
0743-7463
Idioma:
Inglés
Tipo de recurso:
Artículo publicado
Clasificación temática:
Resumen
4-Mercaptopyridine (4MPy) self-assembled on Au(111) has been studied by in situ electrochemical scanning tunneling microscopy (EC-STM) in HClO4, cyclic voltammetry, X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT). Samples prepared by varying the immersion time at constant concentration named short time (30 s) and long time (3 min) adsorption have been studied. Cyclic voltammetry and XPS showed that the chemistry of the adsorbed molecules does not depend on the adsorption time resulting in a well established chemisorbed thiol self-assembled monolayer on Au(111). EC-STM study of the short time adsorption sample revealed a new self-assembled structure after a cathodic desorption/readsorption sweep, which remains stable only if the potential is kept negative to the Au(111) zero charge potential (EPZC). DFT calculations have shown a correlation between the observed structure and a dense weakly adsorbed phase with a surface coverage of θ = 0.4 and a (5 × √3) lattice configuration. At potentials positive to the EPZC, the weakly adsorbed state becomes unstable, and a different structure is formed due to the chemisorption driven by the electrostatic interaction. Long time adsorption experiments, on the other hand, have shown the typical (5 × √3) structure with θ = 0.2 surface coverage (chemisorbed phase) and are stable over the whole potential range. The difference observed in long time and short time immersion can be explained by the optimization of molecular interactions during the self-assembly process.
Palabras clave:
Gold
,
Mercaptopyridine
,
In Situ Stm
,
Electrochemistry
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Articulos(INIFTA)
Articulos de INST.DE INV.FISICOQUIMICAS TEORICAS Y APLIC.
Articulos de INST.DE INV.FISICOQUIMICAS TEORICAS Y APLIC.
Articulos(INQUIMAE)
Articulos de INST.D/QUIM FIS D/L MATERIALES MEDIOAMB Y ENERGIA
Articulos de INST.D/QUIM FIS D/L MATERIALES MEDIOAMB Y ENERGIA
Citación
Herrera, Santiago Esteban; Tasca, Federico; Williams, Federico José; Calvo, Ernesto Julio; Carro, Pilar; et al.; Surface Structure of 4-Mercaptopyridine on Au(111): A New Dense Phase; American Chemical Society; Langmuir; 33; 38; 9-2017; 9565-9572
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