Nanoscopic characterization of two-dimensional (2D) boron nitride nanosheets (BNNSs) produced by microfluidization

Abstract

A microfluidizer high pressure fluid processor is successfully conducted for the first time to exfoliate few layer two dimensional (2D) boron nitride nanosheets (BNNSs) from micro-sized hexagonal boron nitride (h-BN) precursors of large flakes. The mixture of N,N-dimethylformamide and chloroform is conducted as solvent. In determination of to what extent the high pressure microfluidizer successfully assisted with exfoliation of 2D BNNSs from h-BN precursors of large flakes, secondary electron-scanning electron microscopy (SE-SEM) imaging, bright field-transmission electron microscopy (BF-TEM) imaging, energy filtering (EF)TEM-3 window elemental mapping, electron energy loss spectroscopy (EELS), high resolution (HR)TEM imaging and nano beam electron diffraction (NBED) techniques are carried out. Based on the nanoscopic-scale evidences of few layer 2D BNNSs through various TEM techniques, the sheets are observed to have micrometer dimensions in plane whereas nanometer dimensions through their thicknesses depending on the number of layers stacked together. More specifically, the thickness of 2D BNNSs is calculated to be around between 8 and 12 nm using EELS analysis. This value suggests that BNNSs are composed of approximately between 20 and 30 monatomic 2D graphene-like h-BN layers. We are in the opinion that this study has thrown new light on fabricating large scale of 2D BNNSs, which is cited as a highly promising nanomaterial of the future to be utilized in a variety of potential industrial applications including optoelectronic nanodevices, functional polymer composites, support films, hydrogen accumulators and electrically insulating substrates