Dresden 2014 – scientific programme

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O: Fachverband Oberflächenphysik

O 83: Graphene: Adsorption, Intercalation, Doping (O jointly with DS, HL, MA, TT)

O 83.7: Talk

Thursday, April 3, 2014, 17:30–17:45, WIL C107

Graphene Oxide Formation by Adsorption and Photolysis of NO₂ and SO₂ on Graphene/Ir(111) — •Stefan Böttcher, Hendrik Vita, and Karsten Horn — Fritz-Haber Institute of the Max-Planck Society, Faradayweg 4-6, 14195 Berlin, Germany

Graphene oxide is a widely discussed precursor for the technological application of graphene-based systems; for example, its controlled reduction into graphene may lead to a tunable band gap. We report on the formation of oxidized graphene layers on Ir(111) by adsorption and photodissociation of NO₂ and SO₂ at low temperatures. Both adsorbates induce atomic oxygen on the surface when irradiated with intense UV light, leading to an oxidation of the graphene layer. The method presented here is expected to be less intrusive compared for example to oxygen bombardment methods. We also believe the photon induced oxidation to be more selective compared to other physical or wet chemical methods. A band gap opening at room temperature is observed, showing that the graphene oxide phase is also stable above 100 K. High quality graphene can be recovered after annealing, judged by the reappearance of its core and valence level spectral features. Apart from the selective formation of the epoxidic phase, the reaction can also be driven towards a metastable oxide phase from NO₂ using low photon flux. SO₂ on the other hand produces fragments upon dissociation, which have a strong influence on the hybridization state of the graphene backbone.