Study of Pd–Al interactions on Pd/AlOx/Al systems during CO adsorption and desorption cycles: XPS and LEIS

The metal–substrate and metal–metal interactions (MSI, MMI) represent important effects which can determine properties of supported catalysts. We investigated Pd–Al bimetallic interactions of Pd thin films vapor deposited onto non-stoichiometric aluminum oxide surfaces by means of X-ray photoelectron spectroscopy (XPS) and low energy ion scattering (LEIS). The formation of a Pd–Al surface alloy phase exhibiting noble metal-like electronic structure was observed. Changes of the Pd 3d and Pd 4d photoemission features and a modification of surface stoichiometry as a function of degree of aluminum surface oxidation as well as during CO adsorption–desorption cycles are discussed.