▎ 摘　　要

We report a method to purify graphene quantum dots size simply by adding ammonium sulfate. The addition of a salt to a heterogeneous GQD suspension results into the sorting of GQD sub-populations with diameters corresponding to 2.7 +/- 1.6, 5.1 +/- 1.5, 13.3 +/- 1.9, and 18.7 +/- 4.4 nm. These GQDs also exhibit different optical properties.