Synthesis of graphene oxide sheets with controlled sizes from sieved graphite flakes

Graphene oxide (GO) sheets with desired sizes and narrow size distribution were synthesized via a modified Hummers method by using sieved graphite flakes as the starting materials. This method outweighs previous post-synthesis fractionation methods in efficiency and scalability; thus it is more promising for large-scale synthesis of size-controlled GO. The as-prepared GO suspensions exhibited size-dependent liquid crystal behavior. The importance of hydrolysis step on exfoliation and preserving the sizes of GO sheets, and the removal of their sulfate species was also discussed.

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