Non-oxidative intercalation and exfoliation of graphite by Brønsted acids

Nina I. Kovtyukhova, Yuanxi Wang, Ayse Berkdemir, Rodolfo Cruz-Silva, Mauricio Terrones, Vincent H. Crespi, Thomas E. Mallouk

Research output: Contribution to journalArticlepeer-review

170 Scopus citations


Graphite intercalation compounds are formed by inserting guest molecules or ions between sp 2-bonded carbon layers. These compounds are interesting as synthetic metals and as precursors to graphene. For many decades it has been thought that graphite intercalation must involve host-guest charge transfer, resulting in partial oxidation, reduction or covalent modification of the graphene sheets. Here, we revisit this concept and show that graphite can be reversibly intercalated by non-oxidizing Brønsted acids (phosphoric, sulfuric, dichloroacetic and alkylsulfonic acids). The products are mixtures of graphite and first-stage intercalation compounds. X-ray photoelectron and vibrational spectra indicate that the graphene layers are not oxidized or reduced in the intercalation process. These observations are supported by density functional theory calculations, which indicate a dipolar interaction between the guest molecules and the polarizable graphene sheets. The intercalated graphites readily exfoliate in dimethylformamide to give suspensions of crystalline single-and few-layer graphene sheets.

Original languageEnglish (US)
Pages (from-to)957-963
Number of pages7
JournalNature Chemistry
Issue number11
StatePublished - Sep 7 2014

All Science Journal Classification (ASJC) codes

  • General Chemistry
  • General Chemical Engineering


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