The role of steps in surface catalysis and reaction oscillations

Abstract

Atomic steps at the surface of a catalyst play an important role in heterogeneous catalysis, for example as special sites with increased catalytic activity. Exposure to reactants can cause entirely new structures to form at the catalyst surface, and these may dramatically influence the reaction by ‘poisoning’ it or by acting as the catalytically active phase. For example, thin metal oxide films have been identified as highly active structures that form spontaneously on metal surfaces during the catalytic oxidation of carbon monoxide. Here, we present operando X-ray diffraction experiments on a palladium surface during this reaction. They reveal that a high density of steps strongly alters the stability of the thin, catalytically active palladium oxide film. We show that stabilization of the metal, caused by the steps and consequent destabilization of the oxide, is at the heart of the well-known reaction rate oscillations exhibited during CO oxidation at atmospheric pressure. Steps are known to be important sites on the surface of heterogeneous catalysts. Now it is shown that the density of steps on a palladium surface can alter its stability, and thus reactivity, and is key to understanding the oscillatory behaviour of the CO oxidation reaction at atmospheric pressure.

Cite this article

Hendriksen, B., Ackermann, M., van Rijn, R. et al. The role of steps in surface catalysis and reaction oscillations. Nature Chem 2, 730–734 (2010). https://doi.org/10.1038/nchem.728

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