Solvothermal-assisted liquid-phase exfoliation of graphite in a mixed solvent of toluene and oleylamine.

Dinh Khoi Dang,Eui Jung Kim

doi:10.1186/s11671-014-0727-9

Abstract

We report an effective method for producing graphene sheets using solvothermal-assisted exfoliation of graphite in a mixed solvent of toluene and oleylamine. The mixed solvent of toluene and oleylamine produces higher yield of graphene than its constituents, oleylamine and toluene. The oleylamine molecules with its long chain enwrap the graphene sheets efficiently, while toluene helps the oleylamine molecules become more flexible and easily intercalate into the edge of graphite. The prepared graphene sheets have a high quality, and the concentration of graphene in the dispersion is as high as 0.128 mg mL−1. The high-quality graphene sheets obtained in this work make them suitable for application in many fields such as energy-storage materials and polymer composites.

Highlights

Graphene, a one-atom thick, two-dimensional monolayer of sp2-bonded carbon, has worldwidely attracted attention of researchers due to its tremendously large surface area, good chemical stability, outstanding electrical conductivity, and high mechanical strength [1,2].It is noticeable that, few existing graphene preparation methods can achieve the defect-free and large-scale production of large-size graphene
By employing solvothermal-assisted exfoliation in a mixed solvent to control the interactions between solvent molecules and sp2 carbon atoms of graphite, we propose a new approach to producing graphene dispersion with high-yield and high-quality graphene sheets
Oleylamine molecules wrap the graphene sheets, which facilitates the exfoliation of graphite during solvothermal process, significantly improving the production yield of graphene

Summary

Background

A one-atom thick, two-dimensional monolayer of sp2-bonded carbon, has worldwidely attracted attention of researchers due to its tremendously large surface area, good chemical stability, outstanding electrical conductivity, and high mechanical strength [1,2]. The sonication-supported exfoliation of graphite in a mixed solvent environment has emerged as a potential method for producing high-quality graphene sheets [14,15]. Aliphatic amines are good solvents for dispersing carbon nanotubes, especially acid-treated carbon nanotubes [16,17,18,19], because they have strong interactions with the sp carbon lattice network of the carbon nanotubes. Benefiting from co-synergistic effect of mixed solvent of oleylamine and toluene, we report an effective method to enhance both the efficiency of the liquidphase exfoliation of graphite and the quality of graphene sheets. By employing solvothermal-assisted exfoliation in a mixed solvent to control the interactions between solvent molecules and sp carbon atoms of graphite, we propose a new approach to producing graphene dispersion with high-yield and high-quality graphene sheets

Methods

Results and discussion

Conclusions