Large-area few-layer hexagonal boron nitride prepared by quadrupole field aided exfoliation

Modification Strategies of Hexagonal Boron Nitride Nanomaterials for Photocatalysis

Although hexagonal boron nitride (h-BN) was initially considered a less promising photocatalyst due to its large band gap and apparent chemical inertness, its unique two-dimensional lamellar structure coupled with high stability and environmental friendliness, as the second largest van der Waals material after graphene, provides a unique platform for photocatalytic innovation. This review not only highlights the intrinsic qualities of h-BN with photocatalytic potentials, such as high stability, environmental compatibility, and tunable bandgap through various modification strategies but also provides a comprehensive overview of the recent advances in h-BN-based nanomaterials for environmental and energy applications, as well as an in-depth description of the modification methods and fundamental properties for these applications. In addition, we discuss the challenges and prospects of h-BN-based nanomaterials for future photocatalysis.

H-BN nanosheets obtained by mechanochemical processes and its application in lamellar hybrid with graphene oxide

Nowadays, hexagonal boron nitride nanosheets (h-BNNS) have shown promising results among 2D nanomaterials. A great effort has been made in recent years to obtain h-BNNS with a high-yield process to enable its large-scale application in industrial plants. In this work, we developed a mechanochemical method for obtaining h-BN nanosheets assisted by NaOH aqueous solution as process aid and aimed the ideal balance between yield, quality and process sustainability. Images obtained by transmission electron microscope suggested a great exfoliation of the h-BNNS in the range of 12-38 layers observed for well dispersed nanosheets. The macroscopic stability study, the polydispersity index, hydrodynamic diameter, and Zeta potential measurements suggested that material prepared in autoclave and ball milling followed by tip sonication process at 40 °C (h-BNNS-T40) could be considered the most promising material. The process used in this case reached a yield of about 37% of nanosheets with an optimal balance between quality and practicality. A hybrid lamellar material was also prepared by drop-casting and dip-coating techniques. An increase on thermal stability in oxidizing atmosphere was observed with respect to the pure graphene oxide (GO). Fourier transformation infrared spectroscopy and RAMAN suggested the presence of chemical interactions between h-BNNS and GO in the hybrid. This fact supports the interest of extending the study of this hybrid (which has an easy preparation method) to further explore its applicability.

Methods of hexagonal boron nitride exfoliation and its functionalization: covalent and non-covalent approaches

The exfoliation of two-dimensional (2D) hexagonal boron nitride nanosheets (h-BNNSs) from bulk hexagonal boron nitride (h-BN) materials has received intense interest owing to their fascinating physical, chemical, and biological properties. Numerous exfoliation techniques offer scalable approaches for harvesting single-layer or few-layer h-BNNSs. Their structure is very comparable to graphite, and they have numerous significant applications owing to their superb thermal, electrical, optical, and mechanical performance. Exfoliation from bulk stacked h-BN is the most cost-effective way to obtain large quantities of few layer h-BN. Herein, numerous methods have been discussed to achieve the exfoliation of h-BN, each with advantages and disadvantages. Herein, we describe the existing exfoliation methods used to fabricate single-layer materials. Besides exfoliation methods, various functionalization methods, such as covalent, non-covalent, and Lewis acid-base approaches, including physical and chemical methods, are extensively described for the preparation of several h-BNNS derivatives. Moreover, the unique and potent characteristics of functionalized h-BNNSs, like enhanced solubility in water, improved thermal conductivity, stability, and excellent biocompatibility, lead to certain extensive applications in the areas of biomedical science, electronics, novel polymeric composites, and UV photodetectors, and these are also highlighted.