Ultralight, Recoverable, and High-Temperature-Resistant SiC Nanowire Aerogel

Ultralight ceramic aerogels with the property combination of recoverable compressibility and excellent high-temperature stability are attractive for use in harsh environments. However, conventional ceramic aerogels are usually constructed by oxide ceramic nanoparticles, and their practical applications have always been limited by the brittle nature of ceramics and volume shrinkage at high temperature. Silicon carbide (SiC) nanowire offers the integrated properties of elasticity and flexibility of one-dimensional (1D) nanomaterials and superior high-temperature thermal and chemical stability of SiC ceramics, which makes it a promising building block for compressible ceramic nanowire aerogels (NWAs). Here, we report the fabrication and properties of a highly porous three-dimensional (3D) SiC NWA assembled by a large number of interweaving 3C-SiC nanowires of 20-50 nm diameter and tens to hundreds of micrometers in length. The SiC NWA possesses ultralow density (∼5 mg cm^-3), excellent mechanical properties of large recoverable compression strain (>70%) and fatigue resistance, refractory property, oxidation and high-temperature resistance, and thermal insulating property (0.026 W m^-1 K^-1 at room temperature in N₂). When used as absorbents, the SiC NWAs exhibit an adsorption selectivity of low-viscosity organic solvents with high absorption capacity (130-237 g g^-1). The successful fabrication of such an attractive material may provide promising perspectives to the design and fabrication of other compressible and multifunctional ceramic NWAs.