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

Abstract

We present an efficient and straightforward covalent functionalization protocol for modification of surface supported graphene and graphite using aqueous reagents.

Self-limiting covalent modification of carbon surfaces: diazonium chemistry with a twist

“…Hence it readily follows that the I(D)/I(G) ratios for functionalized HOPG are lower compared to that for functionalized single layered graphene. 6,17 The I(D)/I(G) ratio obtained here for NBD is comparable to that reported by us recently using electrochemical grafting for the same NBD concentration. 38 Table 1 provides the I(D)/I(G) ratios for the different systems studied here.…”

“…The salt undergoes decomposition to yield a highly reactive aryl radical that attaches itself to the surface with concomitant loss of nitrogen (N2) gas in a process commonly referred to as grafting. Although the aryldiazonium salts are known to undergo spontaneous decomposition in the presence of certain substrates 2 , very often their reductive decomposition is initiated using electrochemical, 3 photochemical 4 or chemical 5,6 means as the latter methods provide a greater degree of control over the grafting process. Covalently modified surfaces prepared using diazonium chemistry have potential applications in diverse range of fields including sensing, 7 catalysis, 8 energy storage systems, 9 anti-icing surfaces, 10,11 to name a few.…”

“…Both homogeneous and heterogeneous reductive processes have been used. Iodide-, 6 and hypophosphorus acid 27,28 mediated dediazoniation and subsequent grafting occurs under homogeneous conditions where the reducing agent and the diazonium salt are in the same phase whereas iron powder-mediated reduction 29,30 involves a two-phase process. The external reducing agents have been proposed to work via two distinct mechanisms (vide infra).…”

“…This latter facet is particularly important given the growing interest in the application of diazonium chemistry for the covalent functionalization of 2D materials. 6,[12][13][14][15] In general, simple chemical protocols that yield densely grafted monolayers of aryl groups are highly sought after.…”

Surface functionalization of nanomaterials by aryl diazonium salts for biomedical sciences

“…This reaction involves the formation of an aryl radical [33] upon dediazonation. This dediazonation can be spontaneous, for example by reaction with the solvent, or triggered by the transfer of an electron from a reducing agent [34] or an electrode [35][36] but it can also be driven by photochemistry. [37][38][39] The surface modification of NPs for biomedical applications can be achieved with diazonium salts in two ways, [40] as depicted in Figure 1.…”