Constructing BN/BN composite aerogels with strong hydrophobic properties and improved heat transfer capability

Boron nitride (BN) aerogels is a class of three-dimensional (3D) hierarchical network structure assembled from BN micro/nanostructures. The construction of BN/BN composite aerogel by introducing of BN micro/nano-structural units into the 3D BN aerogel scaffold provides an effective strategy for obtaining BN aerogel with improved all-round properties. Here, a novel kind of BN/BN composite aerogels has been developed by vacuum impregnation of ammonia borane (AB) into fiber-based BN aerogels, followed by high-temperature pyrolysis. The introducing of AB into BN aerogels makes the formation of unique AB/BN composite aerogels, and the high-temperature decomposition of AB results in the obtaining of a series of multifunctional composites, i.e. BN/BN composite aerogels. As compared with the porous BN microfibers in original BN aerogel, the self-assembled fibers in BN/BN composite aerogel are densely covered with high crystalline BN nanoflakes, which are generated by the AB decomposition. The obtained BN/BN composite aerogels have shown excellent thermal stability, significantly improved hydrophobic effect and heat transfer capability. This work provides a new idea for the future research and development of BN composite aerogels.