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.Furthermo re,the as-exfoliated BNNSs we re 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.