Chemical Functionalization of Graphene Nanoplatelets with Hydroxyl, Amino, and Carboxylic Terminal Groups

As the most studied two-dimensional material, graphene is still attracting a lot of attention from both academia and industry due to its fantastic properties such as lightness, excellent mechanical strength, and high conductivity of heat and electricity. As an important branch of graphene materials, graphene nanoplatelets show numerous applications such as in coating, fillers of polymer composites, energy conversion and storage devices, sensing, etc. Chemical functionalization can introduce different functional groups to graphene nanoplatelets and can potentially endow them with different properties and functions to meet the increasing demand in the fields mentioned above. In this minireview, we present an overview of the research progress of functionalized graphene nanoplatelets bearing hydroxyl, amino, and carboxylic terminal groups, including both covalent and noncovalent approaches. These terminal groups allow subsequent functionalization reactions to attach additional moieties. Relevant characterization techniques, different applications, challenges, and future directions of functionalized graphene nanoplatelets are also critically summarized.