Artículo
Thermal and Chemical Stability of n-Hexadecanethiol Monolayers on Au(111) in O2 Environments
Cometto, Fernando Pablo
; Ruano Sandoval, Gustavo Daniel
; Soria, Federico Ariel
; Calderon, Cecilia Andrea
; Paredes Olivera, Patricia
; Zampieri, Guillermo Enrique
; Patrito, Eduardo Martin
Fecha de publicación:
10/2016
Editorial:
Pergamon-Elsevier Science Ltd.
Revista:
Electrochimica Acta
ISSN:
0013-4686
Idioma:
Inglés
Tipo de recurso:
Artículo publicado
Clasificación temática:
Resumen
Understanding the mechanisms of degradation of self-assembled monolayers (SAM) is required for their use in molecular devices and in general in long term applications. In this context, we investigated the thermal and chemical stability of n-hexadecanethiolate (C16T) monolayers on Au(111) exposed to O2. The degradation of the monolayers was followed by electrochemical (EC) techniques, surface enhancement Raman spectroscopy (SERS) and high resolution photoemission spectra (HR-XPS). The C16T monolayers were heated both under N2 and O2 flux up to 480 K for different times. The degradation of the SAM in the presence of O2 is characterized by the appearance of oxidized sulfur species and sulfur atoms on the surface. The formation time in the dipping solution also affects the thermal stability of the monolayer. Molecular dynamics (MD) simulations and density functional theory (DFT) calculations were performed to elucidate the possible degradation mechanisms. MD shows that O2 molecules easily penetrate the monolayer reaching the Au surface. The DFT calculations identified two oxidation mechanisms which involve the S atom and the alpha carbon of the alkylthiolate. Both mechanisms are very exothermic. The oxidation of the sulfur atom produces a sulfinate which does not alter the monolayer structure. On the contrary, the oxidation of the alpha carbon induces the breakage of the S[sbnd]C bond, the adsorption of atomic S and the desorption of the alkyl chain as an aldehyde.
Palabras clave:
Alkanethiols
,
Au
,
Dft
,
Molecular Dynamics
,
Self-Assembly
,
Stability
Archivos asociados
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Identificadores
Colecciones
Articulos(IFIS - LITORAL)
Articulos de INST.DE FISICA DEL LITORAL
Articulos de INST.DE FISICA DEL LITORAL
Articulos(INFIQC)
Articulos de INST.DE INVESTIGACIONES EN FISICO- QUIMICA DE CORDOBA
Articulos de INST.DE INVESTIGACIONES EN FISICO- QUIMICA DE CORDOBA
Citación
Cometto, Fernando Pablo; Ruano Sandoval, Gustavo Daniel; Soria, Federico Ariel; Calderon, Cecilia Andrea; Paredes Olivera, Patricia; et al.; Thermal and Chemical Stability of n-Hexadecanethiol Monolayers on Au(111) in O2 Environments; Pergamon-Elsevier Science Ltd.; Electrochimica Acta; 215; 10-2016; 313-325
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