Functionalized self-assemble alkanethiol monolayers on Au(111) electrodes:2. Silver electrodeposition

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