Soluble graphene through edge-selective functionalization
Edge-selective functionalization, graphene, energy filtered transmission electron microscopy (EFTEM), chemically- assisted exfoliation
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.
Tsinghua University Press
Zhengzong Sun,Shin-ichiro Kohama,Zengxing Zhang,Jay R. Lomeda,James M. Tour, Soluble graphene through edge-selective functionalization. NanoRes.2010, 3: 117–125