New insights into the solubility of graphene oxide in water and alcohols

Abstract

aOne of the main advantages of graphene oxide (GO) over its non-oxidized counterpart is its ability to form stable solutions in water and some organic solvents. At the same time, the nature of GO solutions is not completely understood; the existing data are scarce and controversial. Here, we demonstrate that the solubility of GO, and the stability of the as-formed solutions depend not just on the solute and solvent cohesion parameters, as commonly believed, but mostly on the chemical interactions at the GO/solvent interface. By the DFT and QTAIM calculations, we demonstrate that the solubility of GO is afforded by strong hydrogen bonding established between GO functional groups and solvent molecules.The main functional groups taking part in hydrogen bonding are tertiary alcohols; epoxides play only a minor role. The magnitude of the bond energy values is significantly higher than that for typical hydrogen bonding. The hydrogen bond energy between GO functional groups and solvent molecules decreases in the sequence: water 4 methanol 4 ethanol. We support our theoretical results by several experimental observations including solution calorimetry. The enthalpy of GO dissolution in water, methanol and ethanol is À0.1815 AE 0.0010, À0.1550 AE 0.0012 and À0.1040 AE 0.0010 kJ g À1 , respectively, in full accordance with the calculated trend. Our findings provide an explanation for the well-known, but poorly understood solvent exchange phenomenon.

On the Solvation Behavior of Graphene Oxide in Ethylene Glycol/Water Mixtures

“…This fuels non‐fading interest in developing and study of new media for an efficient dispersion of GO, its thermal and chemical reduction to graphene, producing novel functionalized materials. Unfortunately, fundamental investigations of the GO behavior in organic media are limited to a few fundamental papers . A rapid progress in the study of these systems is complicated by a number of factors, including, among others, extremely poor solubility of GO in most of non‐aqueous solvents ,.…”

“…Unfortunately, fundamental investigations of the GO behavior in organic media are limited to a few fundamental papers. [3][4][5] A rapid progress in the study of these systems is complicated by a number of factors, including, among others, extremely poor solubility of GO in most of non-aqueous solvents. [4,6] In this regard, mixed solvents and in particular organic/water mixtures serve as promising media for dispersing GO and for its modification by means of chemical and physicochemical stresses.…”

Chemically functionalized graphene oxide thin films for selective ammonia Gas sensing

“…Apart from graphene, GO also provide an excellent base for some exciting applications in the field of gas/bio sensing [36,37] and water desalination [38]. The outstanding properties of GO like, dispersibility in water and other solvents [39], large scale fabrication possibility [40], large surface area [41,42] and availability of different functional groups on surface [43] has attracted the interest of research groups. It has been reported that GO surface consists of single sheet with different types of hydrophilic functional groups attached (e.g.…”

Preparation of graphene nanocomposites from aqueous silver nitrate using graphene oxide’s peroxidase-like and carbocatalytic properties

“…Density functional theory (DFT) calculations reveal the potential use of metal-free graphene to stabilize ground state molecules through non-covalent π-π interactions 26 . However, pure graphene does not dissolve in organic or inorganic solvents 27 . Thus, researchers have functionalized the graphene surface with epoxy, hydroxyl, or carboxyl groups to obtain readily soluble graphene oxide (GO) 27,28 .…”