Size-Dependent Properties of Graphene Quantum Dots

Graphene quantum dots (GQDs) are emerging zero-dimensional carbon nanomaterial with excellent properties including chemically inert behavior, little toxicity, tunable fluorescence, and low biocompatibility, making them capable material for various novel applications. GQDs can be developed via two major strategies: “top-down” strategy and “bottom-up” strategy. These strategies further include different synthesis methods which include hydrothermal method, microwave irradiations, acid oxidation, etc. in which variation in the reaction conditions results in the preparation of different size GQDs. The morphology, surface passivation, bandgap, or edge effects may get altered by varying the size of GQDs which further leads to tuning the properties of GQDs. Heteroatom doping or surface functionalization of GQDs will improve the structural, electronic, and optical properties like chemical behavior, optical activity, and electronic framework of GQDs by modifying their intrinsic properties. The result of various characterizations for different sized GQDs like transmission electron microscopy, X-ray photoelectron spectroscopy, atomic force microscopy, Raman spectroscopy, etc. has been discussed in detail to comprehend the effect of size on structural properties. In this chapter, we have discussed the impact of particle size, shape, and edge defects on the structural, electronic, magnetic, and optical properties of GQDs in detail.