Influence of Step Geometry on the Reconstruction of Stepped Platinum Surfaces under Coadsorption of Ethylene and CO.
We demonstrate the critical role of the specific atomic arrangement at step sites in the restructuring processes of low-coordinated surface atoms at high adsorbate coverage. By using high-pressure scanning tunneling microscopy (HP-STM) and ambient-pressure X-ray photoelectron spectroscopy (AP-XPS), we have investigated the reconstruction of Pt(332) (with (111)-oriented triangular steps) and Pt(557) surfaces (with (100)-oriented square steps) in the mixture of CO and C2H4 in the Torr pressure range at room temperature. CO creates Pt clusters at the step edges on both surfaces, although the clusters have different shapes and densities. A subsequent exposure to a similar partial pressure of C2H4 partially reverts the clusters on Pt(332). In contrast, the cluster structure is barely changed on Pt(557). These different reconstruction phenomena are attributed to the fact that the 3-fold (111)-step sites on Pt(332) allows for adsorption of ethylidyne-a strong adsorbate formed from ethylene-that does not form on the 4-fold (100)-step sites on Pt(557).
Zhongwei
Z
Zhu
⊥Chemical Physics of Materials, Faculty of Sciences, Université Libre de Bruxelles, Campus de la Plaine CP 243, 1050 Bruxelles, Belgium.
Cédric
C
Barroo
Leonid
L
Lichtenstein
Baran
B
Eren
Cheng Hao
CH
Wu
Baohua
B
Mao
⊥Chemical Physics of Materials, Faculty of Sciences, Université Libre de Bruxelles, Campus de la Plaine CP 243, 1050 Bruxelles, Belgium.
Thierry
T
Visart de Bocarmé
#School of Physical Science and Technology, ShanghaiTech University, Shanghai, 200031, China.
Zhi
Z
Liu
⊥Chemical Physics of Materials, Faculty of Sciences, Université Libre de Bruxelles, Campus de la Plaine CP 243, 1050 Bruxelles, Belgium.|⊗Department of Chemical Engineering and Bioengineering, Washington State University, Pullman, Washington 99163, United States.
Norbert
N
Kruse
Miquel
M
Salmeron
Gabor A
GA
Somorjai
ambient-pressure X-ray photoelectron spectroscopy; high-pressure scanning tunneling microscopy; platinum; step orientation; surface reconstruction