Water-Soluble Graphite Nanoplatelets Formed by Oleum Exfoliation of Graphite

A facile route to water-soluble graphite nanoplatelets that uses graphite as the starting material is described. The method relies on the addition of phenyl radicals with subsequent sulfonation of the phenyl groups. Atomic force microscopy, high-resolution transmission electron microscopy, and scanning tunneling microscopy images show that a high degree of exfoliation occurs during the sulfonation step. The sheet resistance of the bulk films of the nanoplatelets prepared by vacuum filtration using an anodisc membrane was found to be 212 Ω/sq.