Single sheet functionalized graphene by oxidation and thermal expansion of graphite

Michael J. McAllister, Je Luen Li, Douglas H. Adamson, Hannes C. Schniepp, Ahmed A. Abdala, Jun Liu, Margarita Herrera-Alonso, David L. Milius, Roberto Car, Robert Krafft Prud'homme, Ilhan A. Aksay

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3327 Scopus citations


A detailed analysis of the thermal expansion mechanism of graphite oxide to produce functionalized graphene sheets is provided. Exfoliation takes place when the decomposition rate of the epoxy and hydroxyl sites of graphite oxide exceeds the diffusion rate of the evolved gases, thus yielding pressures that exceed the van der Waals forces holding the graphene sheets together. A comparison of the Arrhenius dependence of the reaction rate against the calculated diffusion coefficient based on Knudsen diffusion suggests a critical temperature of 550 °C which must be exceeded for exfoliation to occur. As a result of their wrinkled nature, the functionalized and defective graphene sheets do not collapse back to graphite oxide but are highly agglomerated. After dispersion by ultrasonication in appropriate solvents, statistical analysis by atomic force microscopy shows that 80% of the observed flakes are single sheets.

Original languageEnglish (US)
Pages (from-to)4396-4404
Number of pages9
JournalChemistry of Materials
Issue number18
StatePublished - Sep 4 2007

All Science Journal Classification (ASJC) codes

  • General Chemistry
  • General Chemical Engineering
  • Materials Chemistry


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