title: Chemical Makeup and Hydrophilic Behavior of Graphene Oxide Nanoribbons after Low-Temperature Fluorination.
abstract: Here we investigated the fluorination of graphene oxide nanoribbons (GONRs) using H2 and F2 gases at low temperature, below 200 °C, with the purpose of elucidating their structure and predicting a fluorination mechanism. The importance of this study is the understanding of how fluorine functional groups are incorporated in complex structures, such as GONRs, as a function of temperature. The insight provided herein can potentially help engineer application-oriented materials for several research and industrial sectors. Direct (13)C pulse magic angle spinning (MAS) nuclear magnetic resonance (NMR) confirmed the presence of epoxy, hydroxyl, ester and ketone carbonyl, tertiary alkyl fluorides, as well as graphitic sp(2)-hybridized carbon. Moreover, (19)F-(13)C cross-polarization MAS NMR with (1)H and (19)F decoupling confirmed the presence of secondary alkyl fluoride (CF2) groups in the fluorinated graphene oxide nanoribbon (FGONR) structures fluorinated above 50 °C. First-principles density functional theory calculations gained insight into the atomic arrangement of the most dominant chemical groups. The fluorinated GONRs present atomic fluorine percentages in the range of 6-35. Interestingly, the FGONRs synthesized up to 100 °C, with 6-19% of atomic fluorine, exhibit colloidal similar stability in aqueous environments when compared to GONRs. This colloidal stability is important because it is not common for materials with up to 19% fluorine to have a high degree of hydrophilicity.
authors.forename: Rebeca
authors.initials: R
authors.lastname: Romero Aburto
authors.forename: Lawrence B
authors.initials: LB
authors.lastname: Alemany
authors.affiliation: ∥Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States.
authors.forename: Thomas K
authors.initials: TK
authors.lastname: Weldeghiorghis
authors.forename: Sehmus
authors.initials: S
authors.lastname: Ozden
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: Peng
authors.affiliation: ⊥Institute of Condensed Matter and Nanosciences (IMCN), Université catholique de Louvain, Louvain-la-Neuve, 1348 Belgium.
authors.forename: Aurélien
authors.initials: A
authors.lastname: Lherbier
authors.affiliation: ⊥Institute of Condensed Matter and Nanosciences (IMCN), Université catholique de Louvain, Louvain-la-Neuve, 1348 Belgium.
authors.forename: Andrés Rafael
authors.initials: AR
authors.lastname: Botello Méndez
authors.forename: Chandra Sekhar
authors.initials: CS
authors.lastname: Tiwary
authors.forename: Jaime
authors.initials: J
authors.lastname: Taha-Tijerina
authors.forename: Zheng
authors.initials: Z
authors.lastname: Yan
authors.forename: Mika
authors.initials: M
authors.lastname: Tabata
authors.affiliation: ⊥Institute of Condensed Matter and Nanosciences (IMCN), Université catholique de Louvain, Louvain-la-Neuve, 1348 Belgium.
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Charlier
authors.forename: James M
authors.initials: JM
authors.lastname: Tour
authors.forename: Pulickel M
authors.initials: PM
authors.lastname: Ajayan
keywords: 19F−13C MAS NMR; DFT calculations; fluorinated graphene; fluorination; graphene nanoribbons; graphene oxide