Electrophoretic size fractionation of graphene oxide nanosheets

Abstract

This work reports, for the first time, the fractionation of bulk polydispersed graphene oxide (GO) into several fractions of highly monodispersed nanosheets with the smallest fraction having an average size of ∼40 nm and an area of 0.2 × 10⁴ nm² by a non-gel electrophoresis technique. Compared with other fractionation techniques, the size distribution of the fractions is narrower and much more uniform. The summation of the number of nanosheets in each fraction is roughly equal to the total number of sheets in the bulk. We show, for the first time, that the smallest fraction possesses photoluminescence properties. The characterization techniques applied on each fraction showed a wide distribution of varying properties not seen in the bulk including quantum dot behavior for the fraction with the narrowest size distribution. The theoretical dependence of the electrophoretic mobility and sheet size was evaluated for each fraction with different surface charge densities. This method is simple, cheap, and fast which can be used in the large scale preparation of monodispersed GO.