Raman signatures of bulk aqueous dispersions of single-layer graphene, "eau de graphene"
Résumé
We have recently described how metastable aqueous dispersions of single layer graphene (SLG) can be
prepared simply by transferring SLG, prepared by oxidation of fully exfoliated graphenide, into water, with no
surfactant.1 The aqueous graphene dispersions are named eau de Graphene (EdG) to convey the idea of water
with only graphene inside.
Here, we report the intrinsic Raman signatures of graphene dispersed in EdG and we show that they
correspond to all the expected characteristics of SLG. We stress the difference in these signatures with respect to
those of the natural graphite precursor and to those of some aqueous dispersions of few-layers graphene (FLG)
stabilized by surfactants. We discuss the Raman shifts of the G and 2D band in terms of doping and strain of the
graphene flakes2,3. Finally, by comparing the second order Raman signatures (D and D’ bands)3 of EdG and those
of corresponding thin films, we discuss the nature and amount of defects on the graphene sheets.4,5 All together
this provides a full description of the structure and properties of graphene flakes dispersed in water without any
additive.