Graphene is a single layer of graphite, so it is only one atom thick. Each carbon atom is bonded to three others in hexagonal rings, and one electron from each atom is delocalised. The strong covalent bonds make graphene very strong, and the delocalised electrons let it conduct electricity. This makes it useful in electronics and in composites, where it is added to other materials to strengthen them.
Fullerenes are molecules of carbon atoms with hollow shapes, such as balls and tubes. Their structure is based on hexagonal rings of carbon atoms, but they may also contain rings of five or seven carbon atoms. The first fullerene to be discovered was Buckminsterfullerene, which has the formula C60 and a spherical shape.
Carbon nanotubes are cylindrical fullerenes with a very high length to diameter ratio. Their properties make them useful in nanotechnology, electronics and materials. For example, they can be used to strengthen materials without making them much heavier.
