Photochemical Functionalization of Graphene Oxide by Thiol-Ene Click Chemistry

Graphene oxide (GO) is an important platform that can be functionalized, notably because of its wide variety of functional groups. Functionalization is a critical step, leading to the production of GO-based materials for promising applications in many fields ranging from biomedicine, depollution, to energy storage. Defects introduced into the graphitic domain during graphite oxidation allow to obtain alkene groups, which can be functionalized via thiol-ene click reactions (TER). Usually, for GO functionalization by TER, thermal radical initiators have been used with disadvantages such as high reaction times and the subsequent GO reduction, losing possible oxygen functional groups that can be further used for a second functionalization. Hence, we introduce the photochemical functionalization of GO by TER, with cysteamine as the probe molecule, using a photoinitiator. The reaction was characterized by attenuated total reflection-Fourier transform infrared spectroscopy, UV spectroscopy, fluorimetry, X-ray photoelectron spectroscopy, and Raman spectroscopy. This new perspective of photoinduced TER provides advantages such as short reaction times, use of mild conditions, and avoiding a subsequent GO reduction, associated with efficient orthogonal functionalization.