Synthesis of Water Soluble Graphene

Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
Nano Letters (Impact Factor: 13.59). 07/2008; 8(6):1679-82. DOI: 10.1021/nl080604h
Source: PubMed

ABSTRACT A facile and scalable preparation of aqueous solutions of isolated, sparingly sulfonated graphene is reported. (13)C NMR and FTIR spectra indicate that the bulk of the oxygen-containing functional groups was removed from graphene oxide. The electrical conductivity of thin evaporated films of graphene (1250 S/m) relative to similarly prepared graphite (6120 S/m) implies that an extended conjugated sp (2) network is restored in the water soluble graphene.

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    • "In this technique, graphene layers are exfoliated by the mechanical energy provided by bath or horn sonication , which breaks the van der Waals interactions between graphene layers. At the same time, surfactant molecules are adsorbed onto the graphene layers surface and prevent their re-stacking via steric repulsions [25] [30] [31] (see Fig. 1A). The main advantage of using this approach for ECAs application is that we are able to preserve the single layer structure of graphene and prevent their re-stacking inside the nanocomposite without disturbing its structure. "
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    ABSTRACT: We report sodium dodecyl sulfate (SDS) stabilization of graphene nanosheets, with two different sizes as auxiliary fillers inside the conventional electrically conductive adhesive (ECA) composite. Using this non-covalent modification approach we were able to preserve the single-layer structure of graphene layers and prevent their re-stacking inside the composite, which resulted in a significant electrical conductivity improvement of ECAs at noticeably low filler content. Addition of 1.5 wt% small and large SDS-modified graphene into the conventional ECAs with 10 wt% silver flakes led to low electrical resistivity values of 5.5 × 103 Ω.cm and 35 Ω.cm, respectively, while at least 40 wt% of silver flakes was required for the conventional ECA to be electrically conductive. A highly conductive ECA with very low bulk resistivity of 1.6 × 10-5 Ω.cm was prepared by adding 1.5 wt% of SDS-modified large graphene into the conventional ECA with 80 wt% silver flakes which is less than that of eutectic lead-based solders.
    Carbon 09/2015; 91:188-199. DOI:10.1016/j.carbon.2015.04.039 · 6.20 Impact Factor
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    • "With the increasing demand for graphene-based materials, especially in the fields of energy storage and catalysis that can endure defects to some extent and uncertainty of the layer numbers, thermal or chemical exfoliation is more appealing. However, the chemical exfoliation, which always employs extra agents, such as hydrazine hydrate [31], NaBH 4 [17], hydroquinone [32], metal Fe [33] or ascorbic acid [34] in the reduction step, often introduces heteroatomic species. Furthermore, the exfoliation in organic solvents often meets the problem of solvent removal since most of them have high boiling point. "
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    • "The thermal and chemical reductions methods have been employed so far to reduce GO. For chemical reduction different reducing agents such as hydrogen sulphide [9],hy- drazine [10] [11],sodiumborohydride[12], dimethylhydrazine [13] and hydroquinone [14] are widely used. But as the field effect mobility of reduced GO (rGO) is smaller than that of exfoliated graphene [15] [16] [17] and reducing agents used for reduction are hazardous. "
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    ABSTRACT: Films of graphene oxide (GO) and amide functionalized graphene oxides (AGOs) were deposited on SiO2/Si(100) by spin coating and were thermally annealed at different temperatures. Sheet resistance of GO and AGOs films was measured using four probe resistivity method. GO an insulator at room temperature, exhibits decrease in sheet resistance with increase in annealing temperature. However, AGOs' low sheet resistance (250.43 Ω) at room temperature further decreases to 39.26 Ω after annealing at 800 °C. It was observed that the sheet resistance of GO was more than AGOs up to 700 °C, but effect was reversed after annealing at higher temperature. At higher annealing temperatures the oxygen functionality reduces in GO and sheet resistance decreases. Sheet resistance was found to be annealing time dependent. Longer duration of annealing at a particular temperature results in decrease of sheet resistance.
    Thin Solid Films 06/2015; 585(1). DOI:10.1016/j.tsf.2015.03.037 · 1.76 Impact Factor
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