title: 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.
authors: Kamerlingh Onnes Laboratory, Leiden University, PO Box 9504, 2300 RA Leiden, The Netherlands.
authors: Bas L M
authors: BL
authors: Hendriksen
authors: Marcelo D
authors: MD
authors: Ackermann
authors: Richard
authors: R
authors: van Rijn
authors: Dunja
authors: D
authors: Stoltz
authors: Ioana
authors: I
authors: Popa
authors: Olivier
authors: O
authors: Balmes
authors: Andrea
authors: A
authors: Resta
authors: Didier
authors: D
authors: Wermeille
authors: Roberto
authors: R
authors: Felici
authors: Salvador
authors: S
authors: Ferrer
authors: Joost W M
authors: JW
authors: Frenken
mesh_terms: D002248:Carbon Monoxide / Q000737:chemistry*; D002384:Catalysis; D007700:Kinetics; D009716:Numerical Analysis, Computer-Assisted; D010165:Palladium / Q000737:chemistry*; D013499:Surface Properties; D014961:X-Ray Diffraction
chemical_list: D010165:Palladium; D002248:Carbon Monoxide; C048320:palladium oxide