The Electronic Interaction of Pt-Clusters with ITO and HOPG Surfaces upon Water Adsorption

Abstract

Abstract In order to investigate the catalytic properties of supported platinum clusters, their interaction with water was monitored using photoelectron spectroscopy. The clusters were exposed to up to five Langmuir of water at cryogenic temperatures. Additionally, the influence of the substrate was studied by employing HOPG and ITO as complementary support materials. In contrast to bulk platinum a distinct chemical shift is observable in the Pt4f binding energies for Pt clusters deposited on ITO. The same clusters on HOPG show no changes in binding energy. We propose that this trend is due to a change in the surface Fermi level in ITO, hence highlighting the strong interaction between the platinum cluster and the substrate material. Therefore it is reasonable to assume, that the catalytic efficiency of these clusters in general can not solely be described by the electronic structure of the cluster alone, but that also the electronic changes induced in the substrate may have a major impact on the catalytic performance as well.