Functionalized self-assembled monolayers and their influence on silver electrodeposition

We have studied the Ag electrodeposition on bare Au and on Au(111) surfaces covered with alkanethiol SAM (self-assembled monolayer) using cyclic voltammetry (CV) and in situ scanning tunneling microscopy (STM). The SAM composition was varied with respect to the alkyl chain length using ethylene or hexylene backbones on the one hand and with respect to the layer termination on the other hand, introducing -CH3, -OH or -SH groups, respectively. The electrochemical and structural studies in absence of silver ions allowed us to know the density of the different SAMs for the further Ag deposition. Differences among the SAMs as well as between the SAMs and bare gold were noted during the Ag bulk deposition. Such differences arc; more remarkable when hexanedithiol is used for the SAM. This molecule is adsorbed by only one thiol moiety whereas the other one remains free and exerts silver/thiolate interactions at the SAM/electrolyte interface. (C) 2002 Elsevier Science B.V All rights reserved.