The pyrrole methodology for the sustainable functionalization of graphene layers

Graphene, a single layer of carbon atoms arranged in a two-dimensional honeycomb lattice, has emerged as one of the most promising materials with exceptional electrical, mechanical, and thermal properties. However, to fully unlock its potential, it is crucial to obtain graphene in its exfoliated form, consisting of a few layers or even single layers. The importance of obtaining graphene lies in its enhanced properties compared to graphite: fewlayered graphene exhibits increased reactivity and accessibility of active sites, crucial for catalytic applications [1] such as fuel cells, water splitting, and chemical sensing. Additionally, in composite materials, exfoliated graphene serves as a reinforcing agent [2], imparting superior mechanical strength and electrical conductivity [3]. Several methods have been developed to obtain few layers graphene [4]: from bulk graphite, known as top-down approach (such as mechanical exfoliation or chemical methods), or synthesizing it directly in its exfoliated form, the so-called bottom-up strategy (like molecular assembly or epitaxial growth). An interesting and accessible approach to obtaining few layers graphene has been recently developed. The pyrrole methodology is characterized by the easy insertion of organic moieties on graphene defects. It is performed by using two approaches: i) mechanical, such as the application of high shear force using a Silverson-type mixer, and ii) chemical, namely the modification of graphene sheets to prevent re-stacking [5-6]. In this contribution, the decoration of graphene flakes with different pyrrole derivatives is reported, along with their full characterization. The results obtained confirm the modification of graphene flakes. The conducted tests indicate a Diels-Alder type grafting reaction of the flakes. However, our primary focus lies on the pyrroles, which, upon oxidation, demonstrate a propensity to act as dienophiles. References [1] V. B. Mbayachi, et al., Results Chem, 3, (2021), 100163. [2] G. Prioglio, et al., Polymers 12(4), (2020), 944. [3] P. Bøggild, et al., 2D mater, 4(4), (2017), 042003. [4] S. S. Shams, et al., Mater Sci Pol, 33(3), (2015), 566–578. [5] V. Barbera, et al., Pure Appl. Chem, 90(2), (2018), 253–270. [6] V. Barbera, et al., Nanomater, 9(1), (2019), 44.