2.9 Graphene and fullerenes

Graphene

Graphene is just one layer of graphite. Each carbon atom is bonded to three others by strong covalent bonds, and has one delocalised electron.

• Very strong, because of the strong covalent bonds in the sheet.
• Conducts electricity very well, because of the delocalised electrons.
• Very thin and light, and almost transparent.

Possible uses: electronics, touch screens and stronger, lighter composite materials.

Buckminsterfullerene, C₆₀

The first fullerene discovered. It is a hollow sphere of 60 carbon atoms, arranged in hexagons and pentagons (like a football). Fullerenes can also contain rings of 5 or 7 carbon atoms.

• C₆₀ is a simple molecule, so the forces between molecules are weak: it is soft and has a much lower melting point than diamond or graphite.
• Molecules can be used to deliver drugs into the body (other molecules can be put inside the cage), as lubricants and as catalysts (large surface area).

Carbon nanotubes

Nanotubes are cylinders of carbon atoms, like a rolled-up sheet of graphene.

• They have a very high length to diameter ratio: very long and very narrow.
• High tensile strength: they are hard to break when stretched.
• Conduct electricity, because of delocalised electrons.

Uses: nanotechnology, electronics, and reinforcing materials such as tennis rackets and bike frames.