Underpotentially Deposited Metal Layers of Silver Provide Enhanced Stability to Self-Assembled Alkanethiol Monolayers on Gold

This letter details a straightforward electrochemical method for increasing the thermal stability of alkanethiol-based self-assembled monolayers (SAMs) on polycrystalline gold surfaces. Ex situ ellipsometry and X-ray photoelectron spectroscopy were used to follow the desorption of SAMs into a heated hydrocarbon solvent over the temperature range 70−105 °C. Alkanethiol-based SAMs on gold surfaces modified by underpotential deposition to contain a one-atom-thick interlayer of silver exhibited greater stabilities toward desorption than did SAMs on native gold surfaces. The underpotentially deposited silver layer in this system acts to increase the level of interaction at the gold/sulfur interface. The described method should be compatible with the wide range of alkanethiols that have been adsorbed onto gold surfaces and should provide related levels of improved stability.