Synthesis, characterization, and applications of graphene quantum dots

Abstract Graphene quantum dots (GQDs), zero-dimensional graphene fragments, continue to gain significant attention due to their unique properties, including quantum confinement-induced photoluminescence, excellent photostability, configurable surface chemistry, solvent dispersibility, bio-friendliness, edge/shape effects, and a highly tunable bandgap. The presence of a bandgap in GQDs results in properties that are significantly different from those of parent graphene lattices. For example, one of the most exciting features of GQDs is its highly stable photoluminescence (a direct consequence of the semiconducting nature), which can be tailored by engineering their size, shape, functionality, and defect density. Owing to GQDs’ exemplary properties, they have been explored for a wide range of potential applications, such as photovoltaics, light-emitting diodes, supercapacitors, batteries, fuel cells, memory devices, nanogenerators, sensors, bioimaging, tissue engineering, and drug delivery systems. This chapter presents an overview of various methods for the synthesis of GQDs, the fundamental principles behind synthetic protocols, the effect of different synthetic protocols on the properties of the resultant GQDs, as well as the application of synthesized GQDs in various fields of scientific and technological relevance, leveraging their engineered properties.