Abstract
Dispersing graphite in water to obtain true (single-layer) graphene in bulk quantity in a liquid has been an unreachable goal for materials scientists in the past decade. Similarly, a diagnostic tool to identify solubilized graphene in situ has been long awaited. Here we show that homogeneous stable dispersions of single-layer graphene (SLG) in water can be obtained by mixing graphenide (negatively charged graphene) solutions in tetrahydrofuran with degassed water and evaporating the organic solvent. In situ Raman spectroscopy of these aqueous dispersions shows all the expected characteristics of SLG. Transmission electron and atomic force microscopies on deposits confirm the single-layer character. The resulting additive-free stable water dispersions contain 400â m2 lâ1 of developed graphene surface. Films prepared from these dispersions exhibit a conductivity of up to 32â kS mâ1.
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Acknowledgements
Support from the Agence Nationale de la Recherche (GRAAL) and the Linde Corporation is acknowledged. A.P. thanks Nacional de Grafite (Brazil) for a gift of natural graphite. This work was carried out within the framework of GDR-I 3217 âgraphene and nanotubesâ.
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G.B. prepared and characterized SLGiw. K.H. and C.D. recorded the AFM images. L.O. and V.M. made the TEM analysis. G.B., E.A., A.P. and C.D. planned the experiments, analysed the experimental data and wrote the manuscript.
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Bepete, G., Anglaret, E., Ortolani, L. et al. Surfactant-free single-layer graphene in water. Nature Chem 9, 347â352 (2017). https://doi.org/10.1038/nchem.2669
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DOI: https://doi.org/10.1038/nchem.2669
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