Mechanism of Hierarchical Porosity Development in Hexagonal Boron Nitride Nanocrystalline Microstructures for Biomedical and Industrial Applications

Abstract

A well-known ceramic material, hexagonal boron nitride (h-BN), has a number of unique properties, including structural and porosity features, that make it suitable for a wide range of industrial applications. Hierarchical porosity and high specific surface area are desirable properties for adsorption processes such as water and air cleaning, hydrogen storage, and drug delivery. These characteristics could be controlled and optimized by synthesis procedures; however, this process requires an understanding of the factors and mechanisms of nanocrystalline h-BN porosity development and textural properties. In this study, we demonstrate that hierarchical porosity displays evidence of the consecutive h-BN synthesis steps and thermal decomposition of intermediants. In addition, evidence shows that h-BN nanosheets can be folded as a result of van der Waals force interactions at elevated temperatures, which is corroborated by a computational modeling. The biocompatibility of the prepared h-BN was also evaluated to confirm the nontoxicity of the material. The results of this research could aid in the optimization and scaling up of an environmentally friendly h-BN synthesis process and assist in the development of new methods for the production of h-BN at a commercial level.

Formation Mechanism and Porosity Development in Porous Boron Nitride

“…Hoffendahl et al 21 indicated the formation of carbon nitride from melamine but referred to the reaction of boron oxide with ammonia to eventually form BN. Among all the above studies, only those of Ramirez Leyva et al 15 and Tian et al 17 cover the formation of porous BN and they link the porosity to gases released during the reaction, as also suggested by our earlier study. 1 A recent study by Höppe and Gross reports ammonium bis(biureto)borate as an intermediate in boron nitride formation using boric acid and urea under N2.…”

“…Few studies investigated the mechanism of porous BN formation via bottom-up synthesis. 1,[14][15][16][17] Most report the formation of hexagonal boron nitride (h-BN), a non-carbonaceous analogue of graphene with relatively low surface area (typically < 200 m 2 g -1 ) and porosity compared to porous BN. 18,19 In all the studies of porous BN, a few reactions have been suggested that account for the formation from boron-and nitrogen-containing precursors, but there is no consensus to date for a comprehensive reaction scheme with respect to the thermal treatment.…”

“…To ensure the deployment of the material at a larger scale, one must be able to tune its properties for a given application, which clearly necessitates an understanding of its formation process. Few studies investigated the mechanism of porous BN formation via bottom-up synthesis. ,− Most report the formation of hexagonal boron nitride ( h -BN), a noncarbonaceous analogue of graphite with relatively low surface area (typically <200 m 2 g –1 ) and porosity compared to porous BN. , In all the studies of porous BN, a few reactions have been suggested that account for the formation from boron- and nitrogen-containing precursors, but there is no consensus to date for a comprehensive reaction scheme with respect to the thermal treatment. In addition, reported syntheses use different reagents, gas atmospheres, and reaction conditions, which impact the formation process and resulting product.…”

“…The two mechanisms may not be mutually exclusive and may also depend on the synthesis parameter space. Under the former mechanism fall, for instance, the studies by Brožek and Hubáček, Ramirez Leyva et al, Wu et al, Tian et al, and Hoffendahl et al The second category includes the work by Gong et al, who used graphene as a precursor. Hoffendahl et al indicated the formation of carbon nitride from melamine but referred to the reaction of boron oxide with ammonia to eventually form BN.…”

Magnetic Nanostructured White Graphene for Oil Spill and Water Cleaning

“…21 For that reason, hexagonal boron nitride (h-BN) was suggested as a biocompatible and less harmful material for human body and many organisms as reported in our previous study. 22 material is commercially called white graphene. It is also a hydrophobic and light material with promising properties for crude oil sorption.…”