Electronic structure effects in catalysis probed by X-ray and electron spectroscopy

Here we review some recent developments in using electron and X-ray spectroscopy measurements to elucidate the chemical bond formation on catalyst surfaces used in chemical energy transformations. The d-band model allows a simple understanding of the bond strength of oxygen atom interacting with transition metals in terms of the energy position of the d-band. It is in particular the population of the antibonding states appearing through the interaction of the d-band with the O 2p orbitals that determines the bond strength. We demonstrate how we can fine tune the d-band position and population of antibonding states for strained Pt films on Cu(1 1 1) and Ag(1 1 1) and ligand affected Pt surfaces due to either Ni, Co or Fe in the subsurface layer. We show the effect of nanostructuring in Pt monolayer model electrocatalysts on a Rh(1 1 1) single-crystal substrate on the adsorption strength of chemisorbed species using In situ high energy resolution fluorescence detection X-ray absorption spectroscopy (HERFD XAS) at the Pt L3 edge.