Stepped and kinked surfaces

The Pt(lll) surface continues to show undetectable activity as the oxygen content increases, although the activity passes through a maximum for both the stepped and kinked surfaces with increasing oxygen content. 

Figure 3. The other common imperfection site on a (111) surface is a kink. This 7(111) X (310) surface shown in perspective is a regularly stepped and kinked surface with a step sequence beginning every seventh row and with a kink site at every third atom in the row. The atoms in kink sites have a coordination number of six...

Figure 5. The flat stepped and kinked surfaces of platinum. (Photo credit Lawrence Berkeley Laboratories. Reproduced with permission from ref. 5. Copyright 1980 Elsevier Science Publishers.)...

Results for stepped and kinked surfaces also given. 

Until this point, the use of low-index crystal surface electrodes has allowed to get insight into the electrocatalytic phenomena. However, real surfaces are far from being perfect and comprise several types of sites, including step and kink sites, and the size of the ordered domains is rather limited. For that reason, it is also important to rationalize the effect of such sites in the reaction, using stepped and kinked surfaces. Because of its complexity, there are few examples of these effects in the literature, but the research on the subject is expected to become more and more important. 

The presence of defects in a given surface structure may also play an important role in the electrocatalytic process. Normally, long-range ordered domains are separated from each other by step or kink sites. The substrate atoms that belong to kink or step sites have special adsorption properties since they have a lower coordination number, that is, they have a lower number of nearest neighbor substrate atoms than the surface atoms in a well-ordered domain. These properties may result in an increased catalytic activity. In order to model the real surfaces, stepped and kinked surfaces are used since they have a well-defined distribution of these sites and they can be prepared reproducibly. 

A predictive theory of heterogeneous catalysis, therefore, should include the prediction of the restructuring phenomena that occur when a catalyst is brought into its reactive phase. This is especially important when surface roughening occurs with the creation of reactive steps and kinks. Surface reconstruction is driven by the surface s desire to minimize its surface energy. Sometimes a surface which is free of adsorbates will reconstruct its bulk terminated surface, as for instance the hexagonal reconstruction of the Pt(lOO) surface. Surface reconstruction of clean surfaces occurs predominantly on transition metals with spatially extended d-valence atomic orbitals and with high electron occupations such as Pt and Au. 

Adsorption and chemical bonding on high Miller index, stepped and kinked surfaces... 

Jiang T, Mowbray DJ, Dobrin S, Falsig H, Hvolbaek B, Bligaard T, Nprskov JK. Trends in CO oxidation rates for metal nanoparticles and close-packed, stepped, and kinked surfaces. J Phys Chem C 2009 113 10548-10553. 

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