Cyanographene and Graphene Acid: Emerging Derivatives Enabling High-Yield and Selective Functionalization of Graphene

• Published in: ACS nano Vol. 11; no. 3; pp. 2982 - 2991
• Main Authors: Bakandritsos, Aristides, Pykal, Martin, Błoński, Piotr, Jakubec, Petr, Chronopoulos, Demetrios D, Poláková, Kateřina, Georgakilas, Vasilios, Čépe, Klára, Tomanec, Ondřej, Ranc, Václav, Bourlinos, Athanasios B, Zbořil, Radek, Otyepka, Michal
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 28-03-2017
• Subjects: graphene acid; fluorographene chemistry; graphene nitrile; 2D acid; nucleophilic substitution
• ISSN: 1936-0851; 1936-086X
• DOI: 10.1021/acsnano.6b08449

Efficient and selective methods for covalent derivatization of graphene are needed because they enable tuning of graphene’s surface and electronic properties, thus expanding its application potential. However, existing approaches based mainly on chemistry of graphene and graphene oxide achieve only limited level of functionalization due to chemical inertness of the surface and nonselective simultaneous attachment of different functional groups, respectively. Here we present a conceptually different route based on synthesis of cyanographene via the controllable substitution and defluorination of fluorographene. The highly conductive and hydrophilic cyanographene allows exploiting the complex chemistry of −CN groups toward a broad scale of graphene derivatives with very high functionalization degree. The consequent hydrolysis of cyanographene results in graphene acid, a 2D carboxylic acid with pK a of 5.2, showing excellent biocompatibility, conductivity and dispersibility in water and 3D supramolecular assemblies after drying. Further, the carboxyl groups enable simple, tailored and widely accessible 2D chemistry onto graphene, as demonstrated via the covalent conjugation with a diamine, an aminothiol and an aminoalcohol. The developed methodology represents the most controllable, universal and easy to use approach toward a broad set of 2D materials through consequent chemistries on cyanographene and on the prepared carboxy-, amino-, sulphydryl-, and hydroxy- graphenes.