Anomalously Large Reactivity of Single Graphene Layers and Edges toward Electron Transfer Chemistries

Research areas:
  • Uncategorized
Year: 2010
Type of Publication: Article
  • Richa Sharma, Chrisantha J. Perera Joon Hyun Baik
Journal: Nano Letters Volume: 10
Number: 2 Pages: 398-405
Month: FEB 2010
PT: J; TC: 113; UT: WOS:000274338800007
The reactivity of graphene and its various multilayers toward electron transfer chemistries with 4-nitrobenzene diazonium tetrafluoroborate is probed by Raman spectroscopy after reaction on-chip. Single graphene sheets are found to be almost 10 times more reactive than bi- or multilayers of graphene according to the relative disorder (D) peak in the Raman spectrum examined before and after chemical reaction in water. A model whereby electron puddles that shift the Dirac point locally to values below the Fermi level is consistent with the reactivity difference. Because the chemistry at the graphene edge is important for controlling its electronic properties, particularly in ribbon form, we have developed a spectroscopic test to examine the relative reactivity of graphene edges versus the bulk. We show, for the first time, that the reactivity of edges is at least two times higher than the reactivity of the bulk single graphene sheet, as supported by electron transfer theory. These differences in electron transfer rates may be important for selecting and manipulating graphitic materials on-chip.