Liquid-phase exfoliation has progressed in recent years to become a common method for production of 2D materials. During exfoliation, surfactants can be used to stabilize the nanosheets against reaggregation. Here, using WS₂ as a model system, we explore the effect of varying surfactant type and concentration on the yield and dimensions of the exfoliated nanosheets. For ionic surfactants, the mass of nanosheets produced was widely constant for low surfactant concentrations but decreased sharply for surfactant concentrations above ∼10 mM, regardless of surfactant. Very similar surfactant–concentration dependence was observed for both nanosheet length and thickness. Contrary to previous reports, this data implies that the optimum surfactant concentration is not linked to the critical micelle concentration. In addition, we found that surfactant concentrations as low as 0.07 mM yielded stable nanosheet dispersions with zeta potentials above 40 mV. By decoupling the exfoliation and stabilization effects of the surfactant, we have shown that it is the (de)stabilization process, rather than the exfoliation process, which links nanosheet concentration, size, and thickness to surfactant concentration.

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表面活性剂选择和浓度对液相剥离纳米片尺寸和产率的影响

近年来，液相剥离已经发展成为生产2D材料的常用方法。在剥落过程中，表面活性剂可用于稳定纳米片，防止其重新聚集。在这里，使用WS ₂作为模型系统，我们探索了表面活性剂类型和浓度变化对剥离的纳米片的产率和尺寸的影响。对于离子型表面活性剂，所生产的纳米片的质量在低表面活性剂浓度下大致恒定，但在表面活性剂浓度高于约10 mM时急剧下降，而与表面活性剂无关。纳米片的长度和厚度都观察到非常相似的表面活性剂-浓度依赖性。与以前的报告相反，该数据暗示最佳表面活性剂浓度与临界胶束浓度无关。此外，我们发现表面活性剂浓度低至0.07 mM可以产生稳定的纳米片分散体，其Zeta电位高于40 mV。通过消除表面活性剂的剥离和稳定作用，