Berlin 2015 – scientific programme

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O: Fachverband Oberflächenphysik

O 21: Graphene: Growth & Intercalation

O 21.5: Talk

Tuesday, March 17, 2015, 11:30–11:45, MA 041

Chemical Functionalization of Graphene via Hyperthermal Molecular Reaction — Girjesh Dubey¹, Roberto Urcuyo¹, Sabine Abb¹, Gordon Rinke¹, Marko Burghard¹, •Stephan Rauschenbach¹, and Klaus Kern^1,2 — ¹Max-Planck-Institute for Solid State Research, Stuttgart, Germany — ²Institut de Physique de la Matière Condensée, EPFL, Lausanne, Switzerland

Covalent functionalization represents a viable pathway for tailoring graphene’s electronic properties, for instance to open a band-gap. It furthermore enables subsequent chemical coupling for applications in molecular diagnostics and molecular electronics. In this study, chemical vapor deposited (CVD) graphene is covalently functionalized though electrospray ion beam deposition (ES-IBD) of hyperthermal molecular cation beams of 4,4-azobis(pyridine). The one-step, room temperature ion-surface reaction process takes place in high vacuum (10⁻⁷ mbar), and requires a threshold kinetic energy of 165 eV of the molecular ions. The covalent attachment of the molecules is proven by the effect of thermal annealing, which removes the intense D peak in the Raman spectrum of the functionalized graphene. Based up X-ray photoelectron spectroscopy data, we conclude that the attached species are azopyridinium groups. A high functionalization degree of 3% of the carbon atoms of graphene is attained after 3-5 hours of ion exposure of 2× 10¹⁴ azopyridinium/cm² of which 50% bind covalently.

G. Dubey et al.: J. Am. Chem. Soc. 136, 13482-13485 (2014)