Exciting H2 Molecules for Graphene Functionalization

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.

Bisson, RégisAix-Marseille University (författare)
Balog, RichardAarhus University (författare)
Groves, Michael N.Aarhus University (författare)
Kolsbjerg, Esber LeonhardAarhus University (författare)
Cassidy, Andrew MartinAarhus University (författare)
Jœrgensen, Jacob HolmAarhus University (författare)
Halkjær, SusanneAarhus University (författare)
Miwa, Jill A.Aarhus University (författare)
Čabo, Antonija GrubišićAarhus University (författare)
Angot, ThierryAix-Marseille University (författare)
Hofmann, PhilipAarhus University (författare)
Arman, AlifLund University,Lunds universitet,MAX IV-laboratoriet,MAX IV Laboratory(Swepub:lu)slju-afa (författare)
Urpelainen, SamuliLund University,Lunds universitet,MAX IV-laboratoriet,MAX IV Laboratory(Swepub:lu)maxl-sua (författare)
Lacovig, PaoloElettra Sincrotrone Trieste (författare)
Bignardi, LucaElettra Sincrotrone Trieste (författare)
Bluhm, HendrikLawrence Berkeley National Laboratory (författare)
Knudsen, JanLund University,Lunds universitet,MAX IV-laboratoriet,Synkrotronljusfysik,Fysiska institutionen,Institutioner vid LTH,Lunds Tekniska Högskola,MAX IV Laboratory,Synchrotron Radiation Research,Department of Physics,Departments at LTH,Faculty of Engineering, LTH(Swepub:lu)slju-jks (författare)
Hammer, BjœrkAarhus University (författare)
Hornekaer, LivAarhus University (författare)
Aarhus UniversityAix-Marseille University (creator_code:org_t)

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