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Chemical Methods for the Generation of Graphenes and Graphene Nanoribbons

Hirsch A, Englert J, Feng X, Mullen K (2011)

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Publication Language: English

Publication Type: Journal article, Original article

Publication year: 2011

Journal

Original Authors: Hirsch A., Englert J.M., Feng X., Müllen K.

Publisher: Wiley-VCH Verlag

Book Volume: 50

Pages Range: A17

Journal Issue: 37

DOI: 10.1002/anie.201190076

Abstract

Chemical entries into the constantly growing general field of graphene can be categorized in two major classes. On the one hand there is the category of top-down approaches starting from easily available graphite sources following the exfoliation route and on the other hand there is the bottom up technique offering atomic precision of produced materials by means of organic synthesis. The top-down approach - capable to produce large amounts of graphenes - is further divided into two strategies resting on d[ferent binding interactions. Non-covalent Jiinctionlization by surjhctants and suitable solvents provides defect free few and single layer graphene in processable dispersions which may be used for all kinds of coating techniques from spray- to simple dip-coating. The exfoliation efficiency of surfactants can be tailored allowing them to fulfill more than their sole dispersion purpose by implementation of electron donating/accepting units. If covalent functionalization is utilized while walking down the "top-down track" one usually does not obtain defect free material as defects in the form of sp -carbon centers are introduced into the graphene lattice. However GICs offer the possibility to minimize possible σ-lattice damage during reductive activation of the parent graphite stack. The obtained reductively exfoliated negatively charged graphene sheets can successively befunctionlized by mild organic oxidants leading to covalent bond formation between the sheets and addend to be introduced. When control about local atomic structure is concerned e.g. in order to define exact optical and electronic properties for narrow graphene nanoribbons, the bottom-up synthetic strategy has to be chosen. Both solution and surface synthesis have been revealed for the successful generation of polyphenylene precursors and following graphene nanoribbons upon intramolecular cyclodehydrogenation process. For both cases, the topology and edge perehery of GNRs are strongly governed by the precursor monomers utilized. Suzuki-type polymerization enables one to synthesize polyphenylene precursors in solution. The introduction of a kinked-backbone and attachment of suitable alkyl chains at specfic positions can improve the solubility of final GNRs in organic solvents which are essential for further solution processing and structural characterizations. Regarding the surjhce-mediated synthesis of GNRs, the precursor monomers with functional halogen groups must be firstly deposited on the surface with monolayer coverage, and then a two step thermal activation process must be performed. While the low temperature treatment in the first step generates the polyphenylene chains via radical addition, a higher temperature is required to fully planarize the precursor by eliminating the hydrogen and affords atomically precise GNRS on the surface. Naturally, extending the width of GNRs by selecting expanded precursor monomers should pave the way to tailoring and engineering the architectures and properties of GNRs. This willfinally bridge the bottleneck of current top-down synthesis of GNRs by means of lithography and chemical etching of graphene. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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APA:

Hirsch, A., Englert, J., Feng, X., & Mullen, K. (2011). Chemical Methods for the Generation of Graphenes and Graphene Nanoribbons. Angewandte Chemie International Edition, 50(37), A17. https://doi.org/10.1002/anie.201190076

MLA:

Hirsch, Andreas, et al. "Chemical Methods for the Generation of Graphenes and Graphene Nanoribbons." Angewandte Chemie International Edition 50.37 (2011): A17.

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