Time-Dependent Structure and Solubilization Kinetics of Graphene Oxide in Methanol and Water Dispersions

Carbonaceous materials have long been attracting attention due to their physical and chemical properties as well as their low production costs. Among them, graphene oxide is considered to be an extremely promising material in the context of a wide spectrum of emerging technologies. However, since graphene oxide is charaterized by a variable and therefore elusive chemical composition, complete control on the structure and the reactivity of this complex material has yet to be achieved, which clearly represents a knowledge gap that needs to be closed in order to confidently enable as many future applications as possible. Here, we present a spectroscopic study of graphene oxide obtained via the Sun method showing structural alteration of the material upon utilization of solvents of different polarity. In particular, our data provide clear experimental evidence that the use of methanol results in a graphene oxide material essentially enriched in carbonyl and hydroxyl groups. Moreover, the conjugated character of the material is also influenced by the nature of the solvent. The observed structural changes, which are due to the functionalization of the graphene basal plane, are time-dependent and correspond to different solubility properties of the resulting material. Finally, the modification of the graphene oxide structure alters the rate and the activation energy of solubilization.