Surface Chemistry of 4‑Mercaptobenzoic Acid Self-Assembled on Ag(111) and Ag Nanoparticles

JULIE V. MAYA GIRÓN; EUGENIA ZELAYA; ALDO A. RUBERT; GUILLERMO A. BENITEZ; PILAR CARRO; ROBERTO C. SALVAREZZA; MARIA E. VELA

JOURNAL OF PHYSICAL CHEMISTRY C

AMER CHEMICAL SOC

Lugar: Washington; Año: 2013 p. 1 - 8

1932-7447

The adsorption of 4-mercaptobenzoic acid (MBA) on Ag(111) and Ag nanoparticles (AgNPs) has been studied by Xray photoelectron spectroscopy (XPS), electrochemical techniques, high-resolution transmission electron microscopy (HRTEM), and density functional theory (DFT) calculations. Results show that MBA molecules adsorb intact on the Ag (111) surface via a thiolate bond, arranged in a (√3 × 4) lattice with coverage θ = 0.25. The phase diagram built using DFT data shows that this lattice is more stable than the dense (√7 × √7)R19.1° MBA lattices on reconstructed Ag(111) surfaces. No significant amounts of sulfide were found neither on the Ag(111) surfaces nor on MBA-protected AgNPs, suggesting that the Ag core@Ag-sulfide shell structure where thiolates could be grafted cannot be applied to the MBAprotected AgNPs. Slow degradation of the MBA protective layer in ambient conditions on the AgNPs results in disulfide formation and AgNP sintering.