Graphene Quantum Dots: Preparations, Properties, Functionalizations and Applications

Abstract Due to its zero-dimensional property, graphene quantum dots (GQDs) has quantum confinement effect on the internal charge, so they show many properties different from the parent two-dimensional graphene, such as strong fluorescence, non-zero band gap and easily soluble in solvents. As a member of the family of carbon materials, GQDs also has biocompatibility and low toxicity, which is one of the reasons why GQDs can be widely used in the biomedical field .The edge effect of GQDs is also particularly important. By modifying the edge of GQDs, the performance of GQDs can be regulated. A lot of preparation technology of GQDs, probably can be divided into three categories, and top-down, bottom-up and chemical method, chemical method is different from other literature classification, mainly considering the certain of the preparation of GQDs way, not directly to block materials or direct synthesis of small molecule materials for GQDs, but through intermediate in chemical means under the action of changes and form GQDs. The detailed introduction of the optical, electrical, thermal and magnetic properties of GQDs is the premise of the performance regulation of GQDs. In addition to inheriting the excellent properties of graphene, GQDs also expand the properties of the parent material. The functionalization of GQDs mainly includes the doping technology of introducing heteroatom and the composite technology of combining with other substances to improve the performance of other substances. The performance of these functionalized products is also discussed. The original and functionalized properties of GQDs are based on the application of GQDs. In recent years, GQDs has been used in many fields, including optics, electricity, optoelectronics, biomedicine, energy, agriculture and some emerging interdisciplinary fields. Through the introduction and discussion of the recent research achievements of GQDs, this review mainly highlights the huge potential value of GQDs and puts forward the direction of the development of GQDs in the future.