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Steric effects in O2 chemisorption and catalytic CO oxidation on stepped Pt(111) surfaces have been investigated by scanning a narrow alignment-controlled O2 beam across a curved Pt(111) surface, on which the densities of \{100\} (A-type) and \{111\} (B-type) steps vary smoothly with the distance from the center of the crystal. The contribution of trapping-mediated and activated chemisorption to these processes on the terraces and steps were discussed based on the dependence of these processes on the kinetic energy (80-500 meV) and alignment of O2. The results indicate that (i)the probability of activated O2 chemisorption on surfaces with type-B steps is slightly lower than that on surfaces with type-A steps, (ii) CO oxidation proceeds both at terraces and steps at the sample temperature of 693 K while it happens only at terraces at 423 K. The results of CO oxidation experiments at 423 K indicate that the rate of CO2 production at terraces of the stepped Pt(111) surface is lower than at a flat (111) surface and depends on the step structure.

Rights:

• Creative Commons BY-NC Attribution-NonCommercial 4.0 International
  

Keyword: molecular oxygen , platinum, step, alignment, CO oxidation

Date published: 2024-12-19

Publisher: American Chemical Society (ACS)

Journal:

• The Journal of Physical Chemistry C (ISSN: 19327447) vol. 128 issue. 50 p. 21430-21437

Funding:

• Japan Society for the Promotion of Science 20H02623
• Japan Society for the Promotion of Science 24K01349
• Iketani Science and Technology Foundation 0361245-A

Manuscript type: Author's version (Accepted manuscript)

MDR DOI: https://doi.org/10.48505/nims.5191

First published URL: https://doi.org/10.1021/acs.jpcc.4c06503

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Updated at: 2025-12-06 12:30:27 +0900

Published on MDR: 2025-12-06 08:33:58 +0900