Electrocatalytic Behavior of Pd and Pt Nanoislands Deposited onto 4,4′-Dithiodipyridine SAMs on Au(111)

Abstract

Using different electrochemical techniques as well as in situ scanning tunneling microscopy (STM) and ultraviolet photoelectron spectroscopy (UPS), we investigated the electrocatalytic oxidation of carbon monoxide and methanol on palladium and on platinum nanoislands, which were deposited onto 4,4′-dithiodipyridine self-assembled monolayers (SAMs) on Au(111) single crystal electrodes. Electrochemical and morphological measurements performed on these monoatomic high metal deposits on top of the SAM show rather different island growth along with variations in metal coverage and particle size. UPS He-II valence band spectra of all Pt deposits reveal no intensity at the Fermi energy, so that the resulting nanoislands can be considered as nonmetallic. While the electronic and structural properties do not affect carbon monoxide adsorption, the metal coverage has a tremendous impact on the catalytic activity regarding CO oxidation as well as methanol oxidation.