Raman signatures of single layer graphene dispersed in degassed water, "'Eau de Graphene'"

Abstract

We report a detailed Raman study of single layer graphene dispersed in degassed water without additives (SLGiw), so-called "'eau de graphene"' (EdG). The most characteristic signature of SLGiw is a narrow (28 ± 2 cm") and symmetric 2D band. The intensity of the D band is dominated by the contribution of sp3 defects due to slight functionalization of the basal-planes. The density of defects is estimated in the range 200-650 ppm by studying thin films prepared from EdG. These defects can be fully and easily cured by annealing the films at 800 °C. The position of the G and 2D bands, blue-shifted with respect to pristine SLG, are assigned to moderate biaxial compressive strain (≈0.09 ± 0.02%) and likely weak n doping (<4 × 1012 electrons/cm2) of SLGiw.