Multifunctional ultralight, recoverable, piezoresistive, and super thermal insulating SiC nanowire sponges

Ultralight three-dimensional (3D) architectured silicon carbide (SiC) nanowire sponges with integrated properties of recoverable compressibility, outstanding high-temperature thermal and chemical stability, and fire-retardance have been actively pursued in recent years. However, efficient construction of SiC nanowire sponges with well-controlled overall shapes and distribution of SiC nanowires remains challenging. Herein, by coupling the electrospinning technique and carbothermal reduction process, we have developed a new fabrication process for highly porous and free-standing 3D SiC nanowire (SiCNW) sponges with closely attached nanowires through thermal treatment of stacked electrospun PAN/SiO₂ nanofiber membranes. The resulting SiCNW sponges possess ultralow density (∼29 mg cm⁻³), excellent compressive recoverability from large compressive deformation (up to 40% strain), and fatigue resistance, which endow them with excellent piezoresistive sensing capability under a variety of complex conditions. Furthermore, the sponges display superb thermal insulation (thermal conductivity of 24 mW m⁻¹K⁻¹) and fire-retardance. We believe that the present process provides technical clues for the development of other multifunctional ceramic sponges, and that further development of these ultralight multifunctional ceramic sponges offers potential for the design of advanced components for application in harsh engineering environments.