"Surfactant-free single-layer graphene in water"
George Bepete, Eric Anglaret, Luca Ortolani, Vittorio Morandi, Kai Huang, Alain Pénicaud, Carlos Drummond
NATURE CHEMISTRY (2016) - DOI:10.1038/nchem.2669
Published online 28 November 2016
http://www.nature.com/nchem/journal/vaop/ncurrent/pdf/nchem.2669.pdf
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 400 m2 l–1 of developed graphene surface. Films prepared from these dispersions exhibit a conductivity of up to 32 kS m–1.