title: Preparation and characterization of graphene nanoplatelets from natural graphite via intercalation and exfoliation with tetraalkylammoniumbromide.
abstract: A new method for the preparation of graphene nanoplatelets (GNP) from graphite intercalation compounds (GICs) was investigated. Donor-type ternary GICs of natural graphites, lithium ions and tetrahydrofurane (NG-Li-THF) were synthesized via a solution process, with the lithium ions in the GICs then exchanged with different tetra alkyl ammonium cations to expand the interlayer distance (d-spacing) of these GICs. Microwave irradiation of these GICs resulted in the exfoliation of GICs, forming so-called 'worm-like exfoliated graphites.' Sonication of the worm-like exfoliated graphites in acetone resulted in GNPs with different aspect ratios. Powder X-ray diffractometry, scanning electron microscopy and transmission electron microscopy were employed to characterize the GICs and GNPs. It was found that the ion-exchange of NG-Li-THF increased the volume expansion ratios, and the molecular structure of the tetra alkyl ammonium cations affected the aspect ratios of the GNPs after exfoliation.
authors.affiliation: Department of Semiconductor and Chemical Engineering, Chonbuk National University, Jeonju 561-756, Korea.
authors.forename: Quang-Trung
authors.initials: QT
authors.lastname: Truong
authors.forename: Pashupati
authors.initials: P
authors.lastname: Pokharel
authors.forename: Gwang Seok
authors.initials: GS
authors.lastname: Song
authors.forename: Dai-Soo
authors.initials: DS
authors.lastname: Lee