Diamond and graphite, the two well-known allotropes of carbon, were familiar from the ancient times. Fullerenes, the third form of carbon, were discovered in 1985 and carbon nanotubes in 1991. Thus three dimensional (3D) (diamond and graphite), 1D (nanotubes) and 0D (fullerenes) allotropes were known. Since the breakthrough in 2004 that two dimensional allotropes of carbon, graphene has been repor ...