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Visualization of Atomic Processes on Ruthenium Dioxide using Scanning Tunneling Microscopy
Author(s) -
Over H.,
Knapp M.,
Lundgren E.,
Seitsonen A. P.,
Schmid M.,
Varga P.
Publication year - 2004
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200300833
Subject(s) - scanning tunneling microscope , ruthenium , nanotechnology , microscopy , atomic force microscopy , materials science , chemical physics , scanning ion conductance microscopy , scanning probe microscopy , chemistry , scanning confocal electron microscopy , optics , physics , catalysis , organic chemistry
The visualization of surface reactions on the atomic scale provides direct insight into the microscopic reaction steps taking place in a catalytic reaction at a (model) catalyst's surface. Employing the technique of scanning tunneling microscopy (STM), we investigated the CO oxidation reaction over the RuO 2 (110) and RuO 2 (100) surfaces. For both surfaces the protruding bridging O atoms are imaged in STM as bright features. The reaction mechanism is identical on both orientations of RuO 2 . CO molecules adsorb on the undercoordinated surface Ru atoms from where they recombine with undercoordinated O atoms to form CO 2 at the oxide surface. In contrast to the RuO 2 (110) surface, the RuO 2 (100) surface stabilizes also a catalytically inactive c(2×2) surface phase onto which CO is not able to adsorb above 100 K. We argue that this inactive RuO 2 (100)‐c(2×2) phase may play an important role in the deactivation of RuO 2 catalysts in the electrochemical Cl 2 evolution and other heterogeneous reactions.