ABSTRACT
Graphene, a two-dimensional, hexagonal structured carbon crystal, is currently a keen area in application-based research. Its exceptional intrinsic properties make it ideal for next-generation applications. However, difficulty in opening its gapless band structure and challenging processability due to its insoluble nature have limited its scope. Covalent functionalization of graphene addresses both of these issues rendering a relatively soluble material with a certain band-gap which further enhances its usage in real-time applications. Micromolecular and macromolecular covalent functionalization by C–C and C–N bond formation are the major routes to introduce certain functional groups to graphene. Furthermore, functionalization with various atoms and molecules also results in the formation of a stable and functionalized material that can cater vast areas of application. It is worth mentioning that these modifications to graphene can occur at its strained sp2 hybridized edges that aspire to take a sp3 hybridized structure or at sites such as Jahn–Teller and Stone–Wales defects. Introduction of impurities via doping is another route to functionalize graphene in the basal plane which is otherwise a very tricky undertaking. This chapter can provide overview about various covalent functionalization routes. Mechanism of covalent functionalization via various routes is also discussed to provide a comprehensive knowledge of the subject to the reader.
