Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, USA.
Nat Commun. 2013;4:2213. doi: 10.1038/ncomms3213.
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 the fundamental factors governing the liquid exfoliation process and the 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 mixtures 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 the 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 the high yield exfoliation of layered materials.
层状材料（如石墨和过渡金属二卤化物）的剥离成单层或少数层对于基础研究和潜在应用都具有重要意义。在这里，我们报告了对控制液体剥离过程的基本因素的系统研究，以及合理设计共溶剂方法以剥离层状材料。我们表明，杨氏方程可用于预测在甲醇、乙醇、异丙醇和叔丁醇的水混合物中有效剥离石墨和二硫化钼所需的最佳共溶剂浓度。此外，我们发现共溶剂分子大小在剥离产率中起着重要作用，这归因于较大的共溶剂分子提供了更大的空间排斥。我们的研究为层状材料的剥离提供了重要的见解，并为设计环保的高产率剥离层状材料的方法提供了合理的策略。
