Soluble graphene through edge-selective functionalization


Thermally expanded graphite was functionalized with 4-bromophenyl addends using the in situ diazonium formation procedure, and after mild sonication treatment in N,N′-dimethylformamide, thin graphene layers were exfoliated from the bulk graphite. These chemically-assisted exfoliated graphene (CEG) sheets had higher solubility than pristine graphene without any stabilizer additive. More than 70% of these soluble flakes had less than 5 layers. Energy filtered transmission electron microscopy (EFTEM) elemental mapping provided evidence of the edge-selective diazonium functionalization with graphene. A majority of the Br signals came from the edges of the CEG indicating that the basal planes were not highly functionalized. The CEG was also characterized by X-ray photoelectron spectroscopy, atomic force microscopy, Raman spectroscopy, and transmission electron microscopy.


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Correspondence to James M. Tour.

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Sun, Z., Kohama, S., Zhang, Z. et al. Soluble graphene through edge-selective functionalization. Nano Res. 3, 117–125 (2010).

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  • Edge-selective functionalization
  • graphene
  • energy filtered transmission electron microscopy (EFTEM)
  • chemically-assisted exfoliation