Synthesis of Nanostructured Boron Nitride Aerogels by Rapid Pyrolysis of Melamine Diborate Aerogels via Induction Heating: From Composition Adjustment to Property Studies

The development of boron nitride (BN) aerogels with excellent performance, including low density, excellent mechanical properties, superior chemical inertness, and oxidation resistance, is of great significance for their practical applications, especially in harsh environments. However, the main challenge for the large-scale preparation of nanostructured BN aerogels is to simultaneously obtain BN units with high purity and crystallinity, while maintaining their nanostructure characteristics. Herein, we have creatively prepared high-quality BN aerogels by high-temperature pyrolysis of a melamine diborate (M·2B) aerogel precursor via induction heating. The synthesized BN aerogels consist of one-dimensional porous BN microfibers. Induction-derived pyrolysis with a rapid heating rate and an ultrahigh temperature can greatly reduce the growth time of BN nanocrystals, resulting in the maintenance of the purity, crystallinity, and nanostructure feature of BN fiber units simultaneously. As the pyrolysis voltage increases, the thermal stability and oxidation resistance of the BN aerogel have been greatly improved, and its resistivity has increased by at least three orders of magnitude, mainly due to its low carbon and oxygen impurity content and high crystallinity. The as-prepared BN aerogels exhibit excellent comprehensive properties, including superb thermal stability and oxidation resistance, as well as excellent mechanical properties and thermal insulation. Therefore, BN aerogels can find promising applications in energy storage, catalysis, and environmental remediation, especially in harsh working environments.