title: Simultaneous Reduction and Functionalization of Graphene Oxide via Ritter Reaction.
abstract: Graphene oxide, the oxidized form of graphite, is a common precursor to conductive nanosheets and used widely in the preparation of composite materials. GO has the benefits of easy exfoliation and handling, but it tends to aggregate and restack when reduced. One approach to overcoming this undesired aggregation is covalent modification of the nanosheets; however, this typically requires additional reagents and time. Herein, we report the simultaneous reduction and functionalization of graphene oxide using the Ritter reaction such that reduced nanosheets show good conductivity without the aggregation typical of unmodified material. GO reacts with nitriles in strongly acidic conditions to give highly reduced graphene oxide (C:O of 4.38:1) with covalently attached amides, which compatibilizes it to a number of organic solvents. This Ritter-type reaction produces carbocations on the basal plane of graphene oxide, which allows nucleophilic attack by the nitrogen of the nitrile and produces amides upon hydrolysis. The product has sheet resistance (57.60 ± 4.04 kΩ/sq) substantially lower than that of the starting graphene oxide (529.60 ± 10.04 kΩ/sq) and, more importantly, can easily be dispersed in various organic solvents and does not restack into graphite-like materials upon drying. This method yields individual conductive nanosheets that can be readily incorporated into a number of different systems.
authors.affiliation: Department of Chemistry, Case Western Reserve University , Cleveland, Ohio 44106, United States.
authors.forename: Al C
authors.identifier: http://orcid.org/0000-0002-9449-0519
authors.initials: AC
authors.lastname: de Leon
authors.affiliation: Department of Chemistry, Elmhurst College , Elmhurst, Illinois 60126, United States.
authors.forename: Laura
authors.identifier: http://orcid.org/0000-0003-3336-7522
authors.initials: L
authors.lastname: Alonso
authors.affiliation: Department of Radiology, Case Western Reserve University , Cleveland, Ohio 44106, United States.
authors.forename: Joey Dacula
authors.identifier: http://orcid.org/0000-0002-2649-8527
authors.initials: JD
authors.lastname: Mangadlao
authors.affiliation: Department of Macromolecular Science and Engineering, Case Western Reserve University , Cleveland, Ohio 44106, United States.
authors.forename: Rigoberto C
authors.identifier: http://orcid.org/0000-0002-2899-4778
authors.initials: RC
authors.lastname: Advincula
authors.affiliation: Department of Chemistry, Case Western Reserve University , Cleveland, Ohio 44106, United States.
authors.forename: Emily
authors.identifier: http://orcid.org/0000-0001-6187-6135
authors.initials: E
authors.lastname: Pentzer
keywords: Ritter reaction; functionalization; graphene oxide; nitrile; reduction