Cheap, Gram-Scale Fabrication of BN Nanosheets via Substitution Reaction of Graphite Powders and Their Use for Mechanical Reinforcement of Polymers

Fei Liu,Yoshio Bando,Jun Chen,Ningsheng Xu,Dmitri Golberg,Xuebin Wang,Shaozhi Deng,Xiaoshu Mo,Bin Chen,Haibo Gan,Takashi Sekiguchi,Tongyi Guo

doi:10.1038/srep04211

Fei Liu, Yoshio Bando + Show 10 more

Open Access

https://doi.org/10.1038/srep04211

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Abstract

As one of the most important two-dimensional (2D) materials, BN nanosheets attracted intensive interest in the past decade. Although there are many methods suitable for the preparation of BN sheets, finding a cheap and nontoxic way for their mass and high-quality production is still a challenge. Here we provide a highly effective and cheap way to synthesize gram-scale-level well-structured BN nanosheets from many common graphite products as source materials. Single-crystalline multi-layered BN sheets have a mean lateral size of several hundred nanometers and a thickness ranging from 5 nm to 40 nm. Cathodoluminescence (CL) analysis shows that the structures exhibit a near band-edge emission and a broad emission band from 300 nm to 500 nm. Utilization of nanosheets for the reinforcement of polymers revealed that the Young's modulus of BN/PMMA composite had increased to 1.56 GPa when the BN's fraction was only 2 wt.%, thus demonstrating a 20% gain compared to a blank PMMA film. It suggests that the BN nanosheet is an ideal mechanical reinforcing material for polymers. In addition, this easy and nontoxic substitution method may provide a universal route towards high yields of other 2D materials.

Highlights

As one of the most important two-dimensional (2D) materials, BN nanosheets attracted intensive interest in the past decade
This easy and nontoxic substitution method may provide a universal route towards high yields of other 2D materials
Much effort has been devoted to the preparation of 2D BN sheets[15,16,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36], it is still a challenge to effectively fabricate single-crystalline uniformly structured 2D BN sheets with high yield at low cost and without using toxic reagents

Summary

Discussion

By controlling the growth conditions, gram-level BN sheets have been successfully fabricated using different graphite sources. Once the high-temperature reaction was over, all former carbon sites within the graphite’s honeycomb lattice were filled with alternating B and N atoms. This step can be expressed as: B2O2ðgÞz2CðsÞzN2ðgÞ ÀD? If the ratio of graphite powders to the B2O3 powders is too high or low, BCN/BN complexes may be found in the products rather than pure BN sheets. FWHM of the present characteristic peak is only 10 cm[21], which is narrower than that in the former reports (13 cm[21 45, 16] cm cm[21 21, 27] cm and 30 cm[21 47]) It suggests that the BN sheets by the present substitution reaction have better crystalline quality

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