CPM Seminar

Bridging the material gap in surface science:
A theoretical perspective

Jean-Sabin McEwen

Université Libre de Bruxelles

Despite the large progress made in the recent years to provide a sound understanding of various catalytic surface reactions, there still are a number of questions apparently unsolved [1]. One of these open questions concerns the gap between the choice of catalyst in surface science studies and those used in heterogeneous catalysis. Indeed, in surface science, oriented single crystals are mainly used [1] while multi-facetted metal particles are present in catalysis. This gap is often referred to the material gap in surface science.

One way to bridge this so-called material gap is to study catalyzed chemical reactions at surface defects, such as at adatoms, steps or kinked steps which are expected to play a key role in heterogeneous catalysis. This is attributed to a significantly modified geometric and electronic structure at defect sites compared to a flat terrace. In the first part of my talk, I will present a high-resolution x-ray photoelectron spectroscopy study of the adsorption of CO on a Ag covered stepped Pt(355) surface along with corresponding density functional theory calculations, so as to better understand the role of these sites. In the second part of my talk, another study aimed at bridging the material gap in surface science will be presented. Here, we will examine and develop a comprehensive model on the non-linear effects involved in the catalytic formation of water from H₂/O₂ on rhodium as observed in a field ion microscope [2], which reveals the existence of catalytic non-equilibrium oscillatory patterns on a multi-faceted nanostructured surface.

[1] R. Imbihl, Catal. Today 105, 206 (2005).
[2] T Visart de Bocarmé et al., Surf. Interface Anal. 36, 533 (2004).