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Exciting H2 Molecules for Graphene Functionalization

Kyhl, Line; Bisson, Régis; Balog, Richard; Groves, Michael N.; Kolsbjerg, Esber Leonhard; Cassidy, Andrew Martin; Jœrgensen, Jacob Holm; Halkjær, Susanne; Miwa, Jill A. and Čabo, Antonija Grubišić, et al. (2017) In ACS Nano
Abstract
Hydrogen functionalization of graphene by exposure to vibrationally excited H2 molecules is investigated by combined scanning tunneling microscopy, high-resolution electron energy loss spectroscopy, X-ray photoelectron spectroscopy measurements, and density functional theory calculations. The measurements reveal that vibrationally excited H2 molecules dissociatively adsorb on graphene on Ir(111) resulting in nanopatterned hydrogen functionalization structures. Calculations demonstrate that the presence of the Ir surface below the graphene lowers the H2 dissociative adsorption barrier and allows for the adsorption reaction at energies well below the dissociation threshold of the H–H bond. The first reacting H2 molecule must contain... (More)
Hydrogen functionalization of graphene by exposure to vibrationally excited H2 molecules is investigated by combined scanning tunneling microscopy, high-resolution electron energy loss spectroscopy, X-ray photoelectron spectroscopy measurements, and density functional theory calculations. The measurements reveal that vibrationally excited H2 molecules dissociatively adsorb on graphene on Ir(111) resulting in nanopatterned hydrogen functionalization structures. Calculations demonstrate that the presence of the Ir surface below the graphene lowers the H2 dissociative adsorption barrier and allows for the adsorption reaction at energies well below the dissociation threshold of the H–H bond. The first reacting H2 molecule must contain considerable vibrational energy to overcome the dissociative adsorption barrier. However, this initial adsorption further activates the surface resulting in reduced barriers for dissociative adsorption of subsequent H2 molecules. This enables functionalization by H2 molecules with lower vibrational energy, yielding an avalanche effect for the hydrogenation reaction. These results provide an example of a catalytically active graphene-coated surface and additionally set the stage for a re-interpretation of previous experimental work involving elevated H2 background gas pressures in the presence of hot filaments. (Less)
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@article{69c9969d-3d72-4355-a963-d86bdfae8080,
  abstract     = {Hydrogen functionalization of graphene by exposure to vibrationally excited H2 molecules is investigated by combined scanning tunneling microscopy, high-resolution electron energy loss spectroscopy, X-ray photoelectron spectroscopy measurements, and density functional theory calculations. The measurements reveal that vibrationally excited H2 molecules dissociatively adsorb on graphene on Ir(111) resulting in nanopatterned hydrogen functionalization structures. Calculations demonstrate that the presence of the Ir surface below the graphene lowers the H2 dissociative adsorption barrier and allows for the adsorption reaction at energies well below the dissociation threshold of the H–H bond. The first reacting H2 molecule must contain considerable vibrational energy to overcome the dissociative adsorption barrier. However, this initial adsorption further activates the surface resulting in reduced barriers for dissociative adsorption of subsequent H2 molecules. This enables functionalization by H2 molecules with lower vibrational energy, yielding an avalanche effect for the hydrogenation reaction. These results provide an example of a catalytically active graphene-coated surface and additionally set the stage for a re-interpretation of previous experimental work involving elevated H2 background gas pressures in the presence of hot filaments.},
  author       = {Kyhl, Line and Bisson, Régis and Balog, Richard and Groves, Michael N. and Kolsbjerg, Esber Leonhard and Cassidy, Andrew Martin and Jœrgensen, Jacob Holm and Halkjær, Susanne and Miwa, Jill A. and Čabo, Antonija Grubišić and Angot, Thierry and Hofmann, Philip and Arman, Alif and Urpelainen, Samuli and Lacovig, Paolo and Bignardi, Luca and Bluhm, Hendrik and Knudsen, Jan and Hammer, Bjœrk and Hornekaer, Liv},
  issn         = {1936-086X},
  keyword      = {graphene, vibrational excitation, nanostructured functionalization, band gap engineering, molecular hydrogen, catalysis},
  language     = {eng},
  month        = {12},
  publisher    = {The American Chemical Society},
  series       = {ACS Nano},
  title        = {Exciting H2 Molecules for Graphene Functionalization},
  url          = {http://dx.doi.org/10.1021/acsnano.7b07079},
  year         = {2017},
}