Preparation of Few-Layer Graphene Dispersions from Hydrothermally Expanded Graphite

Cristian Vacacela Gomez,Stefano Bellucci,Gabriela Tubon Usca,Hannibal Brito,Adalgisa Tavolaro,Talia Tene,Marco Guevara,Dennys Colcha,Raul Molina

doi:10.3390/app9122539

Abstract

In this study, we propose a novel approach to prepare few-layer graphene (FLG) dispersions, which is realized by exfoliating natural graphite flakes in a surfactant aqueous solution under hydrothermal treatment and liquid-phase exfoliation. In order to obtain stable and well-dispersed FLG dispersions, pristine graphite is hydrothermally expanded in a hexadecyltrimethylammonium bromide (CTAB) aqueous solution at 180 °C for 15 h, followed by sonication up to 3 h. In comparison to long-time sonication methods, the present method is significantly efficient, and most importantly, does not involve the use of an oxidizing agent and hazardous media, which will make it more competent in the scalable production of graphene.

Highlights

Owing to its outstanding physical and chemical properties [1,2], graphene has become the most studied nanomaterial of the past decade
The intercalation increases the interlayer distance of graphite which is crucial to the improvement of the subsequent ultrasonication process [15]
We focus on graphene dispersions obtained at the lowest concentration of CTAB (0.1 mg mL−1 ) and after 3 h of sonication

Summary

Introduction

Owing to its outstanding physical and chemical properties [1,2], graphene has become the most studied nanomaterial of the past decade. Many top-down methods have developed for preparing graphene, such as micromechanical cleavage of graphite [3], oxidation-reduction of graphite [4,5], electrochemical exfoliation of graphite [6], and liquid-phase exfoliation of graphite [7]. The liquid-phase exfoliation is the most commonly used method to prepare graphene by sonication at a low cost and with minimal environmental impact. This method mostly involves the use of high-boiling point solvents, e.g., N-methyl-pyrrolidone (NMP) [8] and a long sonication time to reach high concentrations of dispersed graphene [9]. Surfactants, are excellent candidates in the direct exfoliation of graphite because they are used as a dispersant and a stabilizer

Methods

Results

Conclusion