Surface-structure sensitivity

The studies of ammonia synthesis over Fe and Re and the hydrodesulfurization of thiophene over Mo, described above, illustrate the importance and success of our approach of studying catalysis over single crystal samples at high pressures. The use of surfaces having a variety of orientations allows the study of reactions that are surface structure sensitive 6Uid provides insight into the nature of the catalytic site. Here we have shown that the ammonia synthesis... 

Platinum Nanoclusters Size and Surface Structure Sensitivity of Catalytic Reactions... 

Anong the netal electrodes nith surface structure sensitive proper-tiesjthe first ones to be considered are those nith electrocatalytic activity, such as platinun group netals. Thus platinun is the nost attractive naterial because of its exceptional spectrun of catalytic properties and its good stability in various electrolytic nedia. 

During the last ten years profound changes have occurred in surface science that resulted in the rapid improvement of our understanding of surface structure. Electron, atom and ion scattering techniques proved to be very sensitive to the surface monolayer structure and composition. High intensity photon fluxes can also be employed in ways to obtain high surface structure sensitivity. 

The UPD of Ag on Au and Pt is also an interesting reaction to investigate with surface structure-sensitive techniques. It has clearly been demonstrated that the iodine adlayers on Pt(lll) and Au(lll) strongly affect the UPD of Ag [1, 8, 36]. For example, Fig. 3 illustrates a clear difference in the electrochemical response of the UPD of Ag on a well-defined Pt(l 11) in sulfuric acid (a) and on a Pt(l 11) with the (V X V7)R19.1° iodine adlayer (b), respectively. Two sets of well-defined UPD peaks in the cyclic voltammogram were observed on a well-ordered Pt(lll) in sulfuric acid... 

We will discuss the surface-structure sensitivity of chemical binding of adsorbed atoms and molecules when we review the properties of the surface chemical bond in Chapter 6. 

Recent single-crystal studies reveal the surface-structure sensitivity and anisotropy of self-diffusion (70, 71]. Depending on the structure of the crystal face, diffusion coefficients may vary by orders of magnitude. This is shown for rhodium adatom diffusion on various rhodium crystal faces in Figure 4.14. Diffusion rates parallel to steps are greater than diffusion rates perpendicular to them. 

The vibrational spectra of carbon monoxide chemisorbed on various metal surfaces are a function of coverage and temperature [128]. Review the experimental techniques that were employed and discuss the surface structure sensitivity, the coverage and temperature dependencies of the adsorbed molecule. 

The adsorbate bond is surface-structure-sensitive, and adsorbate-induced surface restructuring frequently occurs. Rough surfaces (with lower atomic coordination) restructure more readily. 

Inert gases decrease the work function of transition metals [53-55]. Although their bonding is weak, they exhibit detectable surface-structure sensitivity. This has been particularly well demonstrated for the adsorption of xenon. Review the available literature and discuss the nature of inert gas bonding to metal substrates that gives rise to these effects. 

R.C. Yeates and G.A. Somorjai. Surface Structure Sensitivity of Alloy Catalysis Catalytic Conversion of /i-Hexane over Au-Pt(lll) and Au-Pt(lOO) Alloy Cry.stal Surfaces. / Catal. 103 208 (1987). 

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