Fullerene Onions
Definition and meaning of Fullerene Onions in chemistry.
Fullerene onions are carbon nanostructures made of multiple closed, spherical fullerene shells nested concentrically inside one another, resembling the layered structure of an onion.
In more detail
They form when carbon soot, nanodiamond, or graphitic particles are subjected to intense electron-beam irradiation (or high-temperature annealing), which drives curved graphitic fragments to close up into successive spherical cages. Each shell is a giant closed fullerene, and adjacent shells sit roughly 0.34 nanometers apart, close to the interlayer spacing of graphite. Also called carbon nano-onions (CNOs) or onion-like carbon (OLC), they are of interest as solid lubricants, supercapacitor and battery electrode materials, and catalyst supports because of their high surface area, chemical stability, and closed-shell structure.
Key facts
| Formula | Concentric Cn shells, e.g. C60@C240@C540 |
|---|---|
| Also Known As | Carbon nano-onions (CNOs), onion-like carbon (OLC) |
| Interlayer Spacing | ~0.34 nm (similar to graphite) |
| Field | Inorganic Chemistry |
A small fullerene onion can be represented as nested shells such as C60@C240@C540, where a buckminsterfullerene core is enclosed by successively larger icosahedral carbon cages.
Frequently asked questions
How are fullerene onions made?
They are commonly produced by irradiating carbon soot or nanodiamond particles with an intense electron beam inside a transmission electron microscope, which anneals graphitic fragments into concentric closed shells; arc-discharge and thermal annealing methods are also used.
How do fullerene onions differ from carbon nanotubes?
Carbon nanotubes are open-ended cylindrical shells, while fullerene onions are closed, roughly spherical shells nested inside one another with no tube-like cavity.