Carbon is one of the most versatile elements: it forms the basis for an enormous number of chemical compounds, it has several allotropes of different dimensionality, and it exhibits many different bonding geometries. For this reason, carbon materials have had a special place in materials research for a long time. Although the three-dimensional forms of carbon—diamond and graphite—are known since ancient times, it took until 1985 before the first low-dimensional carbon allotrope, the quasi-zero-dimensional fullerene, was discovered. Soon after this, in 1991, the one-dimensional carbon nanotubes were brought to the attention of the scientific community, and in 2004 the two-dimensional carbon allotrope, graphene, became experimental reality. Different combinations of carbon allotropes such as fullerene-filled carbon nanotubes (carbon peapods) and graphite intercalated by fullerenes have been made already.