| Autor: |
Amjad B. Mohammad, Kok Hwa LimPresent address: School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 637459., Ilya V. Yudanov, Konstantin M. Neyman, Notker Rösch |
| Zdroj: |
Physical Chemistry Chemical Physics (PCCP); Feb2007, Vol. 9 Issue 10, p1247-1254, 8p |
| Abstrakt: |
We studied computationally the activation of H2 on clean planar (111), (110) and stepped (221) as well as oxygen pre-covered silver surfaces using a density functional slab model approach. In line with previous data we determined clean silver to be inert towards H2 dissociation, both thermodynamically and kinetically. The reaction is endothermic by ∼40 kJ mol−1 and exhibits high activation energies of ∼125 kJ mol−1. However, oxygen on the surface, modeled by the reconstructed surface p(2 × 1)O/Ag(110) that exhibits –O–Ag–O– added rows, renders H2 dissociation clearly exothermic and kinetically feasible. The reaction was calculated to proceed in two steps: first the H–H bond is broken at an Ag–O pair with an activation barrier Ea∼70 kJ mol−1, then the H atom bound at an Ag center migrates to a neighboring O center with Ea∼12 kJ mol−1. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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