A high efficiency method of preparing "white graphene"

Hexagonal boron nitride nano sheet, also known as "white graphene" Due to the similar structure, graphene and boron nitride nano chips have similar properties, such as excellent mechanical and thermal properties, especially thermal conductivity Although graphene has been widely studied in the field of heat conduction, its conductivity limits its application in the field of insulation In contrast, boron nitride nanocomposites have good electrical insulation, so they are especially suitable for heat dissipation materials in the field of heat conduction and insulation Although boron nitride nanoflakes have many excellent properties, so far, their research and application are far inferior to graphene, which is mainly due to the lack of efficient and low-cost preparation technology of boron nitride nanoflakes Because the interaction force between BN layer and BN layer is much stronger than that between graphene, it is more challenging to prepare nano films by stripping hexagonal BN powder in liquid phase Up to now, although there are many methods to prepare boron nitride nanoflakes, such as ball milling, intercalation and chemical stripping, there are still some shortcomings, such as large energy consumption, long process time, low yield, and the need to use expensive or toxic chemical reagents Based on the above reasons, the functional carbon materials team of Ningbo Institute of materials, Chinese Academy of Sciences has invented a method of preparing hexagonal boron nitride nanoflakes by the combination of molten alkali and ultrasonic stripping This stripping method is not only simple in process, cheap in raw materials, low in equipment requirements, but also convenient for large-scale production, which can greatly reduce costs The product is boron nitride nano sheet with an average thickness of about 3 nm, and the yield can reach 19% Through the method of suction filtration, the boron nitride nano sheet forms a layer by layer compact structure The in-plane thermal conductivity of the ultra-thin thermal conductive film of boron nitride nano sheet can reach 58.3 w / m · K, which lays a foundation for the application of boron nitride nano sheet in heat dissipation and thermal management At present, relevant work has been published in the authoritative journal of 2D materials (2D materials, 2017, 4, 025047) and applied for the national invention patent (201710128745 X) The research work was supported by the national "youth thousand talents plan" and the "hundred talents plan" of the Chinese Academy of Sciences, the National Natural Science Foundation (51573201), the Zhejiang public welfare Technology Application Research Plan (2016c31026) and the 3315 innovation team project Production rate, product photo and stripping process diagram of BNN