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Edge-Functionalized Graphene Nanoribbon Frameworks for the Capture and Separation of Greenhouse Gases

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journal contribution
posted on 06.01.2017, 19:50 by Yearin Byun, Moses Cho, Daeok Kim, Yousung Jung, Ali Coskun
We demonstrate a bottom-up synthetic approach for the synthesis of graphene nanoribbon frameworks (GNFs) incorporating edge-functionalized graphene nanoribbons via the Diels–Alder cycloaddition polymerization and a subsequent FeCl3-catalyzed cyclo-dehydrogenation reactions. This approach not only allowed us to precisely position substituents, namely, −OMe (GNF-0), −H (GNF-1), −CF3 (GNF-2), and −F (GNF-3), but also enabled to tune textural properties and gas affinity of resulting frameworks. GNFs exhibited promising physical properties such as high surface areas (up to 755 m2 g–1) and excellent physicochemical and thermal stabilities (up to 400 °C). Narrow pore size distribution and the presence of large aromatic units led to high affinity toward gases such as CO2 (27.4–30.9 kJ mol–1 at 1 bar), CH4 (21.3–26.0 kJ mol–1 at 1 bar), and H2 (6.5–8.2 kJ mol–1 at 1 bar). Notably, GNFs also showed promising CO2/CH4 breakthrough separation performance for natural gas sweetening and landfill gas separations at 298 K. The edge-functionalization of GNFs with −CF3 and −F significantly improved their affinity toward perfluorocarbons and CFCs, which are classified as potent greenhouse gases. Compared to GNF-3, GNF-2 containing −CF3 moieties showed much higher uptake capacity toward CFC-113 (67 wt % at 298 K).