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The Role of Defects in the Local Reaction Kinetics of CO Oxidation on Low-Index Pd Surfaces.

ABSTRACT: The role of artificially created defects and steps in the local reaction kinetics of CO oxidation on the individual domains of a polycrystalline Pd foil was studied by photoemission electron microscopy (PEEM), mass spectroscopy (MS), and scanning tunneling microscopy (STM). The defects and steps were created by STM-controlled Ar(+) sputtering and the novel PEEM-based approach allowed the simultaneous determination of local kinetic phase transitions on differently oriented μm-sized grains of a polycrystalline sample. The independent (single-crystal-like) reaction behavior of the individual Pd(hkl) domains in the 10(-5) mbar pressure range changes upon Ar(+) sputtering to a correlated reaction behavior, and the reaction fronts propagate unhindered across the grain boundaries. The defect-rich surface shows also a significantly higher CO tolerance as reflected by the shift of both the global (MS-measured) and the local (PEEM-measured) kinetic diagrams toward higher CO pressure.

SUBMITTER: Vogel D

PROVIDER: S-EPMC3683887 | biostudies-other | 2013 Jun

REPOSITORIES: biostudies-other

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