Hydrogen adsorption into

Based on measurements of this kind, the lifetimes of titanium nuclear waste containers under Canadian waste disposal conditions have been modeled (30). Since these conditions are expected to be anoxic, the passive corrosion of titanium will be driven by a very slow reaction with water, leading to the possibility of hydrogen adsorption into the metal ... 

For the polycrystal exposed first to near-saturation doses of CO and then to H2, hydrogen adsorption into the 62 state was completely blocked. In addition, no Z-states were formed. Consistent with published spectroscopic characterization which showed that no C-H or 0-H bonds are formed under UHV coadsorption conditions, no CO hydrogenation products could be detected desorbing from the surface during heating. 

A number of metals have the ability to absorb hydrogen, which may be taken into solid solution or form a metallic hydride, and this absorption can provide an alternative reaction path to the desorption of H,. as gas. In the case of iron and iron alloys, both hydrogen adsorption and absorption occur simultaneously, and the latter thus gives rise to another equilibrium involving the transfer of H,<,s across the interface to form interstitial H atoms just beneath the surface ... 

In discussing the reaction pathways, we believe that the general evidence leads to the conclusion that hydrogenolysis proceeds via adsorbed hydrocarbon species formed by the loss of more than one hydrogen atom from from the parent molecule, and that in these adsorbed species more than one carbon atom is, in some way, involved in bonding to the catalyst surface. In the case of ethane, this adsorption criterion is met via a 1-2 mode or a v-olefin mode. Mechanistically it is difficult to see how the latter could be involved in C—C bond rupture in ethane. With molecules larger than ethane, other reaction paths are possible One is via adsorption into the 1-3 mode, and another involves adsorption as a ir-allylic species. 

The experimental results obtained with carbon nanofibers and nanotubes fit into the tendencies obtained with the other type of carbon materials, indicating that hydrogen adsorption on these materials is also taking place by a physisorption process. 

In this chapter, hydrogen adsorption, particularly observed on Pt electrodes, was not treated as an underpotential deposition phenomenon. However, from a theoretical point of view, it may provide a breakthrough insight into underpotential deposition. Since the underpotential deposition ofM on M is quite characteristic among different combinations of M and M, together with a change in the kind of anions in the solution, a theoretical approach, which requires simplification, is still limited, and more experimental clarification is needed for theoretical work. However, the jellium model was successfully used to describe the lattice contraction of adsorbate T1 and Pb on Ag(lll) as underpotential deposition. ... 

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