Density Gradient Ultracentrifugation of Graphene

kayakjokeMechanics

Feb 22, 2014 (3 years and 7 months ago)

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MRSEC

Density
Gradient Ultracentrifugation
of Graphene

Nano Letters
,
9
, 4931 (2009).

Alexander Green and Mark Hersam

National Science Foundation
-
Nanoelectronics Research Initiative Grant DMR
-
0520513


The NSF
-
NRI supplement to IRG
4 of the Northwestern University
MRSEC is developing unique
combinations of materials,
prototype devices, and
experimental tools to study
excitons in carbon
-
based
nanomaterials. The program aims

to explore, understand, and optimize the electrial generation of excitons, their stability,
transport, and exciton
-
exciton interactions in monodisperse carbon nanotubes and
graphene. One major thrust requires the isolation of monodisperse graphene flakes.
This is accomplished in solution using density gradient ultracentrifugation. Stable
graphene dispersions are produced using the bile salt sodium cholate, which promotes
graphite exfoliation and results in graphene
-
surfactant complexes having buoyant
densities that vary with graphene thickness. Graphene dispersions produced using
density differentiation offer superior performance in transparent conductors to those
produced using conventional sedimentation
-
based centrifugation techniques.