Feb 28, 2003
Carbon nanoscrolls roll up for the future
Scientists from the University of California, Los Angeles (UCLA), US, have come up with a low-temperature, catalyst-free technique for making carbon nanoscrolls. The nanoscrolls have a structure related to multiwalled carbon nanotubes, but could well have higher surface areas.
"We originally developed a method to make two-dimensional forms of bismuth telluride and selenide using chemical intercalation and exfoliation," Richard Kaner of UCLA told nanotechweb.org. "On sonicating the colloidal suspensions of layered materials, we observed some nanoscroll-like structures and wondered if this method could be applied to graphite to make carbon nanoscrolls."
To form the scrolls, the scientists intercalated graphite with potassium. Then they exfoliated the material with ethanol to make a dispersion of carbon sheets. Sonicating these sheets caused them to roll up into carbon nanoscrolls. The nanoscrolls had an average diameter of 40 nm and typically contained 40 +/- 15 layers of carbon.
Since, unlike carbon nanotubes, the nanoscrolls had no end caps, the researchers believe that both sides of the carbon sheets may be accessible. This would give the nanoscrolls an extremely high surface area.
"High surface area carbon may find uses as electrodes in batteries or supercapacitors, as storage materials, perhaps for hydrogen, and in carbon-based composites," added Kaner.
Now the researchers are working with UCLA mechanical engineer Thomas Hahn to explore the mechanical properties of composites containing the scrolls. They also plan to test other properties with industrial collaborators at Rockwell, Hughes, Fractal Systems and Nothrup-Grumman.
The researchers reported their work in Science.
About the author
Liz Kalaugher is editor of nanotechweb.org.