During the last decades, carbon has attracted a great deal of scientific and industrial attention due to the discovery of several allotropes (graphene, fullerene, carbon nanotubes [CNTs]), which are characterized by unprecedented physical and chemical properties such as high mechanical strength, extremely high electrical and thermal conductivity, high optical transparency and excellent gas barrier properties. Because of these unique features, carbon materials are widely used as nanofillers for the fabrication of composite materials with applications in several fields (biology, energy storage, transport and aviation, optoelectronics, pharmaceutics, medicine and many others). Fullerenes, for example, are used as electron acceptors for the fabrication of organic solar cells based on semiconducting polymers such as poly-3-hexyl thiophene, which has significantly improved the efficiency of the corresponding devices, reaching values comparable to those of inorganic solar cells. Graphene-based biosensors characterized by remarkable detection efficiency toward certain target molecules have also been manufactured by exploiting the excellent electrical and optical properties of graphene even when present at very low concentrations. The very high specific surface area of CNTs combined with their low electrical resistance and high charge transport capability have allowed the production of high-performance supercapacitors with increased energy storage, powerdelivery capabilities and rather long-life cycle compared to conventional batteries. From the broad family of the carbon-based nanoparticles (NPs), the one that has attracted the most significant attention is graphene, a one-atom-thick planar sheet of sp2-bonded carbon atoms densely packed in a honeycomb crystal lattice. Graphene is the basic building block for graphitic materials of all other dimensionalities (Figure 5.1), because it can be wrapped up into 0D fullerenes, rolled into 1D nanotubes or stacked into 3D graphite [1].