High-concentration solvent exfoliation of graphene.
A method is demonstrated to prepare graphene dispersions at high concentrations, up to 1.2 mg mL(-1), with yields of up to 4 wt% monolayers. This process relies on low-power sonication for long times, up to 460 h. Transmission electron microscopy shows the sonication to reduce the flake size, with flake dimensions scaling as t(-1/2). However, the mean flake length remains above 1 microm for all sonication times studied. Raman spectroscopy shows defects are introduced by the sonication process. However, detailed analysis suggests that predominantly edge, rather than basal-plane, defects are introduced. These dispersions are used to prepare high-quality free-standing graphene films. The dispersions can be heavily diluted by water without sedimentation or aggregation. This method facilitates graphene processing for a range of applications.
Khan
Umar
U
School of Physics and CRANN, Trinity College Dublin, Dublin 2, Ireland.
O'Neill
Arlene
A
Lotya
Mustafa
M
De
Sukanta
S
Coleman
Jonathan N
JN
D002244:Carbon / Q000737:chemistry*; D002498:Centrifugation; D046529:Microscopy, Electron, Transmission; D010316:Particle Size; D012997:Solvents / Q000737:chemistry*; D013010:Sonication / Q000379:methods*; D013059:Spectrum Analysis, Raman; D013314:Stress, Mechanical; D013997:Time Factors; D014867:Water / Q000737:chemistry
D012997:Solvents; D014867:Water; D002244:Carbon