A rational design of cosolvent exfoliation of layered materials by directly probing liquid–solid interaction
U. Halim, C. R. Zheng, Y. Chen, Z. Lin, S. Jiang, R. Cheng, Y. Huang and X. Duan
Nature Commun. 4, 2213 (2013)
Exfoliation of layered materials such as graphite and transition metal dichalcogenides into mono- or few-layers is of signiﬁcant interest for both the fundamental studies and potential applications. Here we report a systematic investigation of fundamental factors governing the liquid exfoliation process and a rational design of a cosolvent approach for the exfoliation of layered materials. We show that Young’s equation can be used to predict the optimal cosolvent concentration for the effective exfoliation of graphite and molybdenum disulphide in water mixture with methanol, ethanol, isopropanol and t-butyl alcohol. Moreover, we ﬁnd that the cosolvent molecular size has an important role in the exfoliation yield, attributed to the larger steric repulsion provided by larger cosolvent molecules. Our study provides critical insight into the exfoliation of layered materials, and deﬁnes a rational strategy for the design of an environmentally friendly pathway to high yield exfoliation of layered materials.