Ultrasound-Assisted Facile Green Synthesis of Hexagonal Boron Nitride Nanosheets and Their Applications

Abstract

In this study, a facile, novel, ecofriendly method has been demonstrated for the fabrication of hexagonal boron nitride nanosheets (h-BNNs) by ultrasound-assisted exfoliation of h-boron nitride (h-BN) using various extracts of plant materials. Plant extract can be used for nanoparticle synthesis by acting as a reducing, capping, and stabilizing agent. Similarly, plant extract can function as a green surfactant by adsorbing on the surface of h-BN and, by weakening the interlayer interaction, slowly exfoliating h-BN in the form of layer h-BNNs. The product of exfoliation was confirmed by characterization with UV–visible spectrophotometry, Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy, transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, atomic force microscopy, and X-ray photoelectron spectroscopy. Phytoexfoliated h-BNNs were applied for the removal of both cationic and anionic dyes from water, as an antioxidant, and to improve mechanical properties of biobased polyurethane composites. Stable dispersibility of h-BNNs in water was confirmed via stability experiments. Compared to that of the pristine h-BN and the control (h-BNNs synthesized using isopropanol), the plant-material-synthesized h-BNNs showed higher removal efficiency for both cationic and anionic dyes. Improved radical scavenging activities and mechanical properties in castor oil-based polyurethane composites were also shown. This novel and facile approach provides a convenient strategy for stable and scalable exfoliation of h-BN, which might find wide applications in different fields.

An overview of boron nitride based polymer nanocomposites

“…[48] An ecofriendly method has been recently developed by B. S. Kim and coworkers for the fabrication of hexagonal boron nitride nanosheets (h-BNNs) by ultrasoundassisted exfoliation of h-boron nitride (h-BN) using various extracts of plant materials. [49] Here, plant extract could be acting as a reducing, capping and stabilizing agent for nanoparticle synthesis. Additionally, Plant extract can also function as a green surfactant by adsorbing on the surface of h-BN and weakening the interlayer interaction, slowly exfoliating h-BN in the form of layer h-BNNs (Figures 2 and 3).…”

An Innovative Method for Large‐Scale Synthesis of Hexagonal Boron Nitride Nanosheets by Liquid Phase Exfoliation

“…The discovery of two dimensional (2D) materials, properties like graphene, increases rapidly in the research field with their remarkable applications [1–3] . Recently, hexagonal boron nitride (h‐BN) is a new invention as 2D material, whose physical properties are very similar to graphite [4,5] .…”

Hydroxylated boron nitride materials: from structures to functional applications

“…The treatment can generate some other defects in HO-BNs. If the temperature reaches 1500°C, the products have to be hydroxylated by the above methods [47][48][49][50][51][52][53] h-BNNSs Sonication-assisted exfoliation It is a facile method to directly exfoliate BN bulk into HO-BNNSs The hydroxyl degree is relatively low For a high hydroxyl degree, some additives have to be introduced, such as, acid, base, salt, etc [31,[55][56][57][58][59][60][61][62][63] Ball-milling-assisted exfoliation Situations similar to ''sonication-assisted exfoliation'' [64][65][66][67][68][69][70][71][72] Hummer's-like routes The use of strong oxidants (i.e., H 2 SO 4 , H 2 O 2 , KMnO 4 , and their mixtures) requires an extra attention Sometimes the oxidization process can lead to the presence of a few by-products of BN dots [73][74][75][76] Multi-step functionalization method It can be divided into two stages: one is from BN to BNNS and then to HO-BNNS, the other is from BN to HO-BN and then to HO-BNNS [82][83][84][85][86][87][88][89][90][91][92] Bottom-up routes It generally requires high temp...…”

“…More recently, it has been demonstrated the efficacy of extracts of natural plants which work as ecofriendly surfactant agents and improve the exfoliation of h-BN into few-layer nanosheets under sonication. The obtained BNNSs result covered by abundant phytochemicals with OH groups [63].…”

“…Various additives have already been investigated to enhance the hydrolyzation via sonication-assisted exfoliation. Addition of HNO 3 [60], NaOH [61], sodium cholate [62], and plant extracts [63] is one of the most efficient strategies. As-prepared HO-BNNSs obtained by a tip-type sonication process under the assistance of sodium cholate can be easily incorporated into thermoplastic polyamide-imide (PAI) in the presence of polyvinyl alcohol (PVA) [62].…”