4 research outputs found
A Straightforward approach to multifunctional graphene
Graphene has been covalently functionalized through a oneâpot reductive pathway using graphite intercalation compounds (GICs), in particular KC8, with three different orthogonally protected derivatives of 4âaminobenzylamine. This novel multifunctional platform exhibits excellent bulk functionalization homogeneity (Hbulk) and degree of addition while preserving the chemical functionalities of the organic addends through different protecting groups, namely: tertâbutyloxycarbonyl (Boc), benzyloxycarbonyl (Cbz) and phthalimide (Pht). We have employed (temperatureâdependent) statistical Raman spectroscopy (SRS), Xâray photoelectron spectroscopy (XPS), magic angle spinning solid state 13Câ
NMR (MASâNMR), and a characterization tool consisting of thermogravimetric analysis coupled with gas chromatography and mass spectrometry (TGâGCâMS) to unambiguously demonstrate the covalent binding and the chemical nature of the different molecular linkers. This work paves the way for the development of smart grapheneâbased materials of great interest in biomedicine or electronics, to name a few, and will serve as a guide in the design of new 2D multifunctional materials
Unifying Principles of the Reductive Covalent Graphene Functionalization
Covalently functionalized
graphene derivatives were synthesized
via benchmark reductive routes using graphite intercalation compounds
(GICs), in particular KC<sub>8</sub>. We have compared the graphene
arylation and alkylation of the GIC using 4-<i>tert</i>-butylphenyldiazonium
and bisÂ(4-(<i>tert</i>-butyl)Âphenyl)Âiodonium salts, as well
as phenyl iodide, <i>n</i>-hexyl iodide, and <i>n</i>-dodecyl iodide, as electrophiles in model reactions. We have put
a particular focus on the evaluation of the degree of addition and
the bulk functionalization homogeneity (<i>H</i><sub>bulk</sub>). For this purpose, we have employed statistical Raman spectroscopy
(SRS), and a forefront characterization tool using thermogravimetric
analysis coupled with FT-IR, gas chromatography, and mass spectrometry
(TGA/FT-IR/GC/MS). The present study unambiguously shows that the
graphene functionalization using alkyl iodides leads to the best results,
in terms of both the degree of addition and the <i>H</i><sub>bulk</sub>. Moreover, we have identified the reversible character
of the covalent addition chemistry, even at temperatures below 200
°C. The thermally induced addend cleavage proceeds homolytically,
which allows for the detection of dimeric cleavage products by TGA/FT-IR/GC/MS.
This dimerization points to a certain degree of regioselectivity,
leading to a low sheet homogeneity (<i>H</i><sub>sheet</sub>). Finally, we developed this concept by performing the reductive
alkylation reaction in monolayer CVD graphene films. This work provides
important insights into the understanding of basic principles of reductive
graphene functionalization and will serve as a guide in the design
of new graphene functionalization concepts
Solvent-driven electron trapping and mass transport in reduced graphites to access perfect graphene
Herein, we report on a significant discovery, namely, the quantitative discharging of reduced graphite forms, such as graphite intercalation compounds, graphenide dispersions and graphenides deposited on surfaces with the simple solvent benzonitrile. Because of its comparatively low reduction potential, benzonitrile is reduced during this process to the radical anion, which exhibits a red colour and serves as a reporter molecule for the quantitative determination of negative charges on the carbon sheets. Moreover, this discovery reveals a very fundamental physicalâchemical phenomenon, namely a quantitative solvent reduction induced and electrostatically driven mass transport of K+ ions from the graphite intercalation compounds into the liquid. The simple treatment of dispersed graphenides suspended on silica substrates with benzonitrile leads to the clean conversion to graphene. This unprecedented procedure represents a rather mild, scalable and inexpensive method for graphene production surpassing previous wet-chemical approaches