Graphene & fullerenes (AQA GCSE Chemistry)

• The structure of graphene consists of a single layer of graphite which is a sheet of carbon atoms covalently bonded forming a continuous hexagonal layer
• It is essentially a 2D molecule since it is only one atom thick
• It has very unusual properties make it useful in fabricating composite materials and in electronics

Graphene structure

Graphene is a truly remarkable material that has some unexpected properties

• Graphene has the following properties:
  • It is extremely strong but also amazingly light
  • It conducts heat and electricity
  • It is transparent
  • It is flexible

• Strength: It would take an elephant with excellent balance to break through a sheet of graphene
  • It is very strong due to its unbroken pattern and the strong covalent bonds between the carbon atoms. Even when patches of graphene are stitched together, it remains the strongest material out there

• Conductivity: It has delocalised electrons which can move along its surface allowing it to conduct electricity
  • It is known to move electrons 200 times faster than silicon
  • It is also an excellent conductor of heat

• Flexibility: Those strong bonds between graphene’s carbon atoms are also very flexible. They can be twisted, pulled and curved to a certain extent without breaking, which means graphene is bendable and stretchable
• Transparent: Graphene absorbs 2.3 percent of the visible light that hits it, which means you can see through it without having to deal with any glare
  • This gives it the potential to be used for making computer screens of the future

• Fullerenes are a group of carbon allotropes which consist of molecules that form hollow tubes or spheres
• The molecules are made of interlocking hexagonal rings, but they can also be rings of five or seven carbons atoms
• Fullerenes can be used to trap other molecules by forming around the target molecule and capturing it, making them useful for targeted drug delivery systems
• They also have a huge surface area and are useful for trapping catalyst molecules onto their surfaces making them easily accessible to reactants so catalysis can take place
• Some fullerenes are excellent lubricants and are starting to be used in many industrial processes
• The first fullerene to be discovered was Buckminsterfullerene which is affectionately referred to as a “Buckyball”
• In this fullerene, 60 carbon atoms are joined together forming 20 hexagons and 12 pentagons which produce a hollow sphere that is the exact shape of a football

Buckminsterfullerene

Buckminsterfullerene was the first fullerene to be discovered as a component of soot. The 1996 Nobel Prize in Chemistry was jointly awarded for its discovery by teams at Rice University in Texas and the University of Sussex

• Graphene can also be rolled into a cylinder to produce an interesting type of fullerene called a nanotube
• These have high tensile strength and are resistant to breaking or stretching
• As in graphene, nanotubes can also conduct electricity which makes them useful in composites and specialised materials, electronics and nanotechnology

Carbon nanotubes

Diagram showing the structure of nanotube produced from a rolled sheet of graphene