Poster

Enhanced chemical reactivity of pristine graphene strongly interacting with a substrate: chemisorbed CO on graphene/Ni(111)

M. Smerieri¹, E. Celasco^1,2, G. Carraro^1,2, A. Lusuan^1,2, J. Pal^1,2, G. Bracco^1,2, M. Rocca^1,2, L. Savio¹, and L. Vattuone^1,2

¹IMEM-CNR, U.O.S. Genova, Via Dodecaneso 33, 16146 Genova (Italy)

²DIFI Università degli Studi di Genova, Via Dodecaneso 33, 16146 Genova (Italy)

Graphene (G) s usually considered a chemically inert material. Theoretical studies of CO adsorption on free standing graphene predict indeed quite low adsorption energies (< 0.1 eV). In spite of that, pioneering work has recently demonstrated that it can be effectively used in gas sensing applications [1,2] while applications in chemistry have been envisaged, too [3-5]. However, to the best of our knowledge, functionalization of G layers was achieved so far only using reactive species, as aryl radicals or atomic hydrogen, or by adsorption at defect sites. When using less reactive environments/adsorbates only physisorption [1,4] was detected at regular graphene sites.

Here we show by Vibrational Spectroscopy and Scanning Tunnelling Microscopy that non dissociative chemisorption of CO occurs at cold, pristine graphene grown on Ni(111). The CO adlayer remains stable up to 125 K, while some coverage survives flashes to 225 K. This unexpected result is qualitatively explained by the modification of the density of states close to the Fermi energy induced by the relatively strong graphene-substrate interaction. The value of the adsorption energy allows to estimate an equilibrium coverage of the order of 0.1 ML at 10 mbar pressure, thus paving the way to the use of graphene as a catalytically active support under realistic conditions.

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