One-Step Synthesis of Hierarchical Boron Nitride Porous Nanomaterials

Porous boron nitride (BN) has shown great promise in the field of molecule separations, particularly for gas sorption applications such as CO₂ capture or H₂ storage. Herein, we report the straightforward synthesis and detailed characterization of high purity, porous, three-dimensional solid constructed from hybrid one-dimensional hexagonal BN (h-BN) nanofibers and two-dimensional h-BN nanosheets. The structure is synthesized through a one-step, template-free, substrate-free polymer-derived ceramic thermolysis of linear B–N backbone polymer¹ in a reduction environment, resulting in porous and mechanically stable interconnected h-BN hierarchical structure. The thermal dehydrogenation, so-called "chemical blowing",² of the polymeric precursor plays a pivotal role in the synthesis process. Comprehensive characterizations, including high-resolution transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy, all confirm the high purity and crystallinity of the resultant BN phase. A theoretical model based on density functional theory (DFT) calculations combined with reactive force field (ReaxFF)³ molecular dynamics simulations is proposed for the formation of this novel hybrid h-BN architecture. To our knowledge, the method presented here represents the first instance of reliable, controllable, and scalable production of h-BN hierarchical structure of its kind. Overall, this approach offers a straightforward route to porous BN production potentially valuable for gas sorption applications in extreme environments.

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