One-pot carboxyl enrichment fosters water-dispersibility of reduced graphene oxide: a combined experimental and theoretical assessment

Graphene, one of the allotropic forms of carbon, has attracted enormous interest in the last few years due to its unique properties. Reduced graphene oxide (RGO) is known as the nanomaterial most similar to graphene in terms of electronic, chemical, mechanical, and optical properties. It is prepared from graphene oxide (GO) in the presence of different types of reducing agents. Nevertheless, the application of RGO is still limited, owing to its tendency to irreversibly aggregate in an aqueous medium. Herein, we disclosed the preparation of water-dispersible RGO from GO previously enriched with additional carboxyl functional groups through a one-pot reaction, followed by chemical reduction. This novel and unprecedentedly reported reactivity of GO toward the acylating agent succinic anhydride (SA) was experimentally investigated through XPS, Raman, FT-IR, and UV-Vis, and corroborated by DFT calculations, which have shown a peculiar involvement in the functionalization reaction of both epoxide and hydroxyl functional groups. This proposed synthetic protocol avoids use of sodium cyanide, previously reported for carboxylation of graphene, and focuses on the sustainable and scalable preparation of a water-dispersible RGO, paving the way for its application in many fields where the colloidal stability in aqueous medium is required.

Automated summary

Graphene and its derivative, reduced graphene oxide (RGO), are attracting great interest due to their unique properties. However, the tendency of RGO to aggregate in water restricts its application. In this study, water-dispersible RGO was prepared through a novel method using graphene oxide (GO) enriched with additional carboxyl groups and followed by chemical reduction. The reactivity of GO with succinic anhydride was experimentally investigated and confirmed through various techniques. This method offers a sustainable and scalable approach for the preparation of water-dispersible RGO, which could have broad applications.