Functionalized Self-Assembled Alkanethiol Monolayers on Au(111) Electrodes: 2. Silver Electrodeposition

We have studied the early stages of Ag electrodeposition from dilute sulfuric acid solutions on modified Au(111) electrodes with cyclic voltammetry and in situ scanning tunneling microscopy. Several differently functionalized short-, medium-, and long-chain alkanethiols were used for electrode modification. Ag underpotential deposition onto such surfaces is hindered depending on chain length, but the differences between self-assembled monolayers with different endgroups were less significant. Two Ag layers are deposited at the thiol/Au(111) interface in an island growth mechanism at underpotentials. Bulk deposition originates almost exclusively at step edges burying the underlying self-assembled monolayer. Oxidative desorption of the organic film is promoted in contact with a Ag + -containing electrolyte as compared to the metal ion free solution.