Chemisorption of CO on N-doped graphene on Ni(111)

The chemical reactivity of single layers of supported graphene (G) is affected by the nature of the underlying
substrate: in particular CO chemisorption occurs on G/Ni(111), while graphene on Cu is inert. Here,
we demonstrate experimentally that doping of the G layer with nitrogen atoms further increases the reactivity
of the G/Ni(111) system towards CO. The doped layer is obtained by sputtering pristine G/Ni(111)
with N2
+ ions. For an
~11% dopant concentration, an additional electron energy loss at 238 meV appears
in the HREEL spectra besides the loss around 256 meV present also on pristine G/Ni(111). The new feature
corresponds to a CO species with a higher desorption temperature and, consequently, a higher adsorption
energy than the one forming on pristine G/Ni(111). At low coverage, the adsorption energy is estimated
to be ~0.85 eV/molecule.