Scalable exfoliation for few-layered hexagonal boron nitride nanosheets (BNNSs) by microwave-assisted expansion and liquid nitrogen intercalation

The low cost and facile scalable exfoliation route for two-dimensional hexagonal boron nitride (h-BN) was still indispensable for potential applications. In this work, we presented a convenient and scalable exfoliation for few-layer BNNSs. Taking advantage of the advantages of swift heating of microwave and ultra low temperature vaporization of liquid nitrogen, bulk h-BN was high-efficiently exfoliated into fewlayer BNNSs. The as-exfoliated BNNSs had a 2-6 nm thickness and approximately 7.91% yield, exhibiting scalable, facile and environment-friendly features. Furthermore, the as-exfoliated BNNSs were applied as additive in oil for reducing friction of oil. The COF of the BNNSs-based grease reduced by 20.10% compared to grease, and the antiwear performance decreased by 55.8% and 45.1% relative to grease and h-BN-based grease. (C) 2020 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.