Scalable high yield exfoliation for monolayer nanosheets

Although two-dimensional (2D) materials have grown into an extended family that accommodates hundreds of members and have demonstrated promising advantages in many fields, their practical applications are still hindered by the lack of scalable high-yield production of monolayer products. Here, we show that scalable production of monolayer nanosheets can be achieved by a facile ball-milling exfoliation method with the assistance of viscous polyethyleneimine (PEI) liquid. As a demonstration, graphite is effectively exfoliated into graphene nanosheets, achieving a high monolayer percentage of 97.9% at a yield of 78.3%. The universality of this technique is also proven by successfully exfoliating other types of representative layered materials with different structures, such as carbon nitride, covalent organic framework, zeolitic imidazolate framework and hexagonal boron nitride. This scalable exfoliation technique for monolayer nanosheets could catalyze the synthesis and industrialization of 2D nanosheet materials. Top-down exfoliation is one of the most promising approaches for the scalable production of 2D materials, but the current techniques are limited by low yield of monolayers. Here, the authors report the exfoliation of graphene and other layered materials via viscous-polymer-assisted ball-milling, leading to a production of graphene products with monolayer percentage up to 97.9% at a yield of 78.3%.

Automated summary

The authors demonstrate a scalable method for producing monolayer nanosheets by ball-milling exfoliation with the assistance of viscous polyethyleneimine (PEI) liquid. By effectively exfoliating graphite into graphene nanosheets, they achieved a high monolayer percentage of 97.9% at a yield of 78.3%. The universality of this technique was proven by successfully exfoliating other layered materials such as carbon nitride, covalent organic framework, zeolitic imidazolate framework, and hexagonal boron nitride.