Facile synthesis and photoluminescence of graphene oxide quantum dots and their reduction products

A simple chemical method of acid treatment has been developed for cutting graphene oxide into graphene oxide quantum dots with controllable size (similar to 3.0 nm). The newly produced graphene oxide quantum dots have high stability and disperse well in water for several months. Bright blue emission, as well as an excitation-dependent photoluminescence activity, is observed in the GOODs. In contrast, the photoluminescence emission of graphene quantum dots obtained by the reduction of graphene oxide quantum dots has a distinctive blue shift when compared with that of the graphene oxide quantum dots. The difference in PL properties between graphene oxide quantum dots and graphene quantum dots can be attributed to the change of the bandgap due to the different size of the isolated sp(2) cluster in the sp(3) matrix of graphene.