Liquid Phase Modifications of Carbon Nanostructures

Carbon nanostructures have garnered immense attention since time immemorial. Owing to the tunability of these nanostructures, scientists look for various modifications to make them desirable for specific applications. The developed carbon nanostructures range from zero-dimensional to three-dimensional, including carbon dots, carbon nanotubes, carbon nanorods, carbon nanospheres, carbon nanofibers, graphene, graphene oxide, and reduced graphene oxide. Modification of these nanomaterials is extensively reported in the liquid phase due to its ease of synthesis, low energy consumption, reproducibility, and scalability. The wide use of these nanostructures is attributed to their phenomenal properties, such as high thermal and electrical conductivity, tuneable band gap, tensile strength, and biocompatibility. Commonly, carbon-based nanostructures are modified in the liquid phase by a top-down or bottom-up approach. Top-down approach comprises methods like electrochemical oxidation, arc discharge, ultrasonic synthesis, laser ablation, and chemical oxidation. Hydrothermal treatment, microwave synthesis, plasma treatment, and template route are some of the methods used under bottom-up approach. This chapter describes various modifications of carbon nanostructures carried out in the liquid phase.