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.