Lateral size selection of surfactant-stabilised graphene flakes using size exclusion chromatography

Aqueous dispersions of graphene, stabilised by a surfactant, have been separated according to lateral flake size using size exclusion chromatography. Transition electron microscopy was used to characterise the flake size as a function of fraction number. While the stock dispersion had a mean lateral flake size of 0.6 μm, the separated fractions displayed clear size separation, with the second and fourteenth fractions displaying mean sizes of ∼1.2 and ∼0.5 μm, respectively. Raman spectroscopy shows the flake D:G intensity ratio to scale inversely with the flake size indicating that any defects present are associated with flake edges rather than basal plane defects.