The sticking probability for H-2 on some transition metals at a hydrogen pressure of 1 bar

Martin Johansson, Ole Lytken, Ib Chorkendorff

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Abstract

The sticking probability for hydrogen on films of Co, Ni, Cu, Ru, Rh, Pd, Ir, and Pt supported on graphite has been measured at a hydrogen pressure of 1 bar in the temperature range 40–200 °C. The sticking probability is found to increase in the order Ni, Co, Ir, Pd, Pt, Rh, and Ru at temperatures below 150 °C, whereas at higher temperatures, the sticking probability for Pd is higher than for Pt. The sticking probability for Cu is below the detection limit of the measurement. The measured sticking probabilities are slightly lower than those obtained at high hydrogen coverage under ultrahigh vacuum conditions. This could be a consequence of the higher hydrogen pressure used here. The apparent desorption energies extracted from the steady-state desorption rate are found to agree reasonably well with published values for the heat of adsorption at high coverage. However, the sticking probability is not related in a simple way to published values for the heat of adsorption at low coverage, with Ru and Rh giving exceptionally high values for the sticking probability. It is suggested that this is due to the presence of adsorption sites with very low desorption energy on Ru and Rh. ©2008 American Institute of Physics.
Original languageEnglish
JournalJournal of Chemical Physics
Volume128
Issue number3
Pages (from-to)034706
ISSN0021-9606
DOIs
Publication statusPublished - 2008

Bibliographical note

Copyright (2008) American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.

Keywords

  • CATALYSTS
  • CHEMISORPTION
  • PT(111)
  • RHODIUM 110 SURFACE
  • DISSOCIATIVE ADSORPTION
  • MOLECULAR-BEAM
  • THERMAL-DESORPTION
  • DESORPTION-KINETICS
  • CARBON-MONOXIDE
  • SINGLE-CRYSTAL SURFACES

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