INVESTIGADORES
RUBERT Aldo Alberto
artículos
Título:
Complex Surface Chemistry of 4-Mercaptopyridine Self-Assembled Monolayers on Au(111)
Autor/es:
E. A. RAMÍREZ; EMILIANO CORTÉS; ALDO A. RUBERT; PILAR CARRO; GUILLERMO A. BENITEZ; MARIA E. VELA; ROBERTO C. SALVAREZZA
Revista:
LANGMUIR
Editorial:
AMER CHEMICAL SOC
Referencias:
Lugar: Washington; Año: 2012 p. 6839 - 6847
ISSN:
0743-7463
Resumen:
The adsorption of 4-mercaptopyridine on
Au(111) from aqueous or ethanolic solutions is studied by
different surface characterization techniques and density
functional theory calculations (DFT) including van der
Waals interactions. X-ray photoelectron spectroscopy and
electrochemical data indicate that self-assembly from 4-
mercaptopyridine-containing aqueous 0.1 M NaOH solutions
for short immersion times (few minutes) results in a 4-
mercaptopyridine (PyS) self-assembled monolayer (SAM) with surface coverage 0.2. Scanning tunneling microscopy images
show an island-covered Au surface. The increase in the immersion time from minutes to hours results in a complete SAM
degradation yielding adsorbed sulfur and a heavily pitted Au surface. Adsorbed sulfur is also the main product when the selfassembly
process is made in ethanolic solutions irrespective of the immersion time. We demonstrate for the first time that a
surface reaction is involved in PyS SAM decomposition in ethanol, a surface process not favored in water. DFT calculations
suggest that the surface reaction takes place via disulfide formation driven by the higher stability of the S−Au(111) system. Other
reactions that contribute to sulfidization are also detected and discussed.