Synthesis, characterization and application of highly crystalline sp$^{2}$ -- bonded boron nitride aerogels

Aerogels have much potential in both research and industrial applications due to high surface area, low density and fine pore size distribution. Here we report a versatile synthesis and thorough structure characterization of three-dimensional aerogels composed of highly crystalline sp$^{2}$ -- bonded BN layers formed by carbothermal reaction. The structure, crystallinity and bonding of the as-prepared BN aerogels were elucidated by x-ray diffraction, nuclear magnetic resonance of $^{11}$B, transmission electron microscopy (TEAM) and resonant soft x-ray scattering. The macroscopic roughness of the aerogel's surface causes it to be superhydrophobic with a contact angle of 155 $\pm$ 3$^{\circ}$ and high oil uptake (up to 1500 wt{\%}). The used BN aerogel can be regenerated by different heat treatments and still maintain the crystalline porous structure and adsorption capacity. The highly crystalline, chemically pure, thermally stable and porous sp$^{2}$ -- boron nitride aerogel is an ideal host for liquids, gases and other nanomaterials.