Berlin 2018 – scientific programme
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DS: Fachverband Dünne Schichten
DS 17: Poster Session I
DS 17.41: Poster
Tuesday, March 13, 2018, 18:15–20:15, Poster B
Revisiting graphene oxide chemistry via spatially-resolved electron energy loss spectroscopy — •Alberto Zobelli1, Anna Tararan1, Ana Benito2, Wolfgang Maser2, and Odile Stéphan1 — 1Laboratoire de Physique des Solides, University of Paris-Sud, CNRS, Orsay, France — 2Instituto de Carboquímica ICB-CSIC, Zaragoza, Spain
The type and distribution of oxygen functional groups in graphene oxide (GO) and reduced graphene oxide (RGO) remain still a subject of great debate. Local analytic techniques are required to access the chemistry of these materials at a nanometric scale. Electron energy loss spectroscopy in a scanning transmission electron microscope can provide the suitable resolution, but GO and RGO are extremely sensitive to electron irradiation. In this work we employ an optimized experimental setup to reduce electron illumination below damage limit. GO oxygen maps obtained at a few nanometers scale show separated domains with different oxidation levels. The C/O ratio varies from about 4:1 to 1:1, the latter corresponding to a complete functionalization of the graphene flakes. In RGO the residual oxygen concentrates mostly in regions few tens of nanometers wide. Specific energy-loss near-edge structures are observed for different oxidation levels. By combining these findings with first-principles simulations we propose a model for the highly oxidized domains where graphene is fully functionalized by hydroxyl groups forming a 2D-sp3 carbon network analogous to that of graphane.