Oxygen reduction at silver monolayer islands deposited on gold substrate

Underpotential deposition (UPD) of Ag on an Au(111) coated with a self-assembled monolayer (SAM) of decanethiol gives Ag islands having monatomic height. After reductive desorption of the SAM, Ag monolayer islands were exposed and their catalytic activities for oxygen reduction were examined by voltammetry and hanging meniscus rotating disk (HMRD) measurements. Comparison of electrochemical properties and STM images of electrodes revealed that an island with less than 750 Ag-atoms showed two-electron reduction and that an island with over than 4000 Ag-atoms is necessary to show the original ability of four-electron reduction. (C) 2003 Published by Elsevier Science B.V.