Controlling CH2 dissociation on Ru(0001) through surface site blocking by adsorbed hydrogen

Harald Kirsch, Xunhua Zhao, Zefeng Ren, Sergey V. Levchenko, Martin Wolf, R. Kramer Campen

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)

Abstract

Understanding the relative stability of CHx species on surfaces is necessary for mechanistic description of much important catalytic chemistry. Here, we experimentally quantify the barrier of the reaction CH2 → CH + H on Ru(0001) in UHV and find an activation energy, 65 ± 6 kJ/mol, that is >4× higher than previous computational results with 0, 1, or 2 coadsorbed H atoms per CH2, i.e. 16 kJ/mol. Employing density functional theory calculations, we show that this disagreement can be reconciled if 3 coadsorbed H atoms per CH2 are present in our experiment. We further demonstrate, by calculating the surface phase diagram for one carbon species on Ru(0001) as a function of H2 chemical potential, that the additional hydrogen surface coverage requires non-equilibrium conditions. Such conditions may be important at the high temperatures and pressures of real catalytic systems.

Original languageEnglish
Pages (from-to)89-96
Number of pages8
JournalJournal of Catalysis
Volume320
Issue number1
DOIs
Publication statusPublished - Dec 2014
Externally publishedYes

Keywords

  • Density functional theory
  • Methane coupling
  • Methane dissociation
  • Sum frequency generation

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