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.

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This study reports a facile and ecofriendly approach for the ultrasound assisted synthesis of silver and iron oxide nanoparticles and their enhanced antibacterial and antioxidant activities. The fenugreek seed extract was used as reducing, capping, and stabilizing agent in the synthesis of nanoparticles. The transmission electron microscopy results showed that nanoparticles synthesized by ultrasonication have a smaller size (~20 nm) as compared to the nanoparticles fabricated by magnetic stirring (~40 nm). The color change of the solution from milky white to brown suggested the formation of silver nanoparticles which was confirmed by the presence of an absorbance peak at 396 nm. The results of powder X-ray diffraction and energy dispersive X-ray spectroscopy confirmed the crystallinity and elements present in nanoparticles synthesized using fenugreek seed extract. Fourier transform infrared analysis showed that the fenugreek seed phytochemicals were coated on the nanoparticle surface. Thermal gravimetric analysis showed the thermal degradation and stability of nanoparticles. Magnetization study of iron oxide nanoparticles confirmed the superparamagnetic nature. The silver nanoparticles showed antibacterial activities against both gram-negative (Escherichia coli) and gram-positive (Staphylococcus aureus) bacteria, while no antibacterial activities were observed for iron oxide nanoparticles. The ultrasound assisted nanoparticles showed higher stability and antibacterial and antioxidant activity compared with the nanoparticles fabricated by magnetic stirring.