Figure 2: Functionalization of carbon-based nanomaterials with photochromic molecules.

The functionalization can be performed through either covalent or non-covalent approaches. Non-covalent modification includes π–π stacking, hydrophobic interaction or electrostatic interaction, which only mildly perturbs the sp2 structure of the carbon allotrope. While covalent functionalization can be done via cycloaddtion, condensation reaction or radical polymerization and so on, offering strong and robust bonding. 0D, zero dimensional; 1D, one dimensional; 2D, two dimensional.