Iodide mediated reductive decomposition of diazonium salts: towards mild and efficient covalent functionalization of surface-supported graphene.

Covalent functionalization of graphene is highly sought after, not only in view of the potential applications of the chemically modified material, but also because it brings fundamental insight into the chemistry of graphene. Thus, strategies that yield chemically modified graphene with densely grafted films of aryl groups via simple experimental protocols have been the focus of intense research. Here we report a mild, straightforward and efficient approach to graphene/graphite functionalization using iodide mediated reductive dediazoniation of aryldiazonium salts. The experimental protocol employs aqueous solutions of the reagents. The reaction proceeds rapidly at room temperature without the need of any environmental or electrochemical control. The covalently modified surfaces were characterized at the nanometer scale using a combination of complementary surface analytical techniques. The degree of covalent functionalization, and the morphology, as well as the thickness of the grafted films were studied at the molecular level using Raman spectroscopy and scanning probe microscopy, respectively. Furthermore, solution phase UV-Vis spectroscopy was employed to understand the mechanistic aspects. This work demonstrates a facile and scalable covalent modification method compatible for both bulk and monolayer functionalization of graphene.