Hydrogen Bonding in Graphene

Effusion measurements are performed to determine the hydrogen concentration and its binding energies in large area graphene. The samples were grown by chemical vapor deposition using deuterium and deuterated methane as readily identifiable isotopes that duplicate hydrogen chemistry. In a second step, graphene is transferred to silicon substrates covered with an oxide layer of different thickness. H binding energies and the H density-of-states distributions are derived from the effusion spectra. The data show a well defined peak in the H density-of-states at 1.97 eV that is influenced by the thickness of the oxide layer. This is discussed in terms of a model that describes the dissociation of C-H bonds.