Mechanically robust SiC aerogel with both electromagnetic absorption and pollutant adsorption via microtube/nanowire structure design

Silicon carbide (SiC) fiber aerogels are promising materials for renewable energy and aerospace applications. However, conventional SiC aerogels often suffer from limitations such as single-pore structures, inadequate mechanical strength, and high production costs, which severely restrict their practical application. Here, we designed and fabricated a hierarchical porous SiC microtube/nanowire composite aerogel derived from kapok fibers via an in situ conversion strategy. This approach directly utilizes kapok hollow fibers to construct SiC microtubules while simultaneously inducing the self-growth of SiC nanowires, achieving controllable hierarchical pore fabrication in a single step. Compared with conventional methods, this strategy significantly simplifies the fabrication process and enhances multifunctional performance through structural synergy. The unique microtube-nanowire heterostructure provides excellent electromagnetic wave (EMW) absorption (minimum reflection loss (RL) of −56.39 dB, effective absorption bandwidth of 6.04 GHz at 2.0 mm) by enhancing interfacial polarization and optimizing impedance matching. The nanowire bridging effect achieves a compressive strength of 2.85 MPa, surpassing the mechanical limits of conventional aerogels. Additionally, the aerogel exhibited excellent thermal insulation (0.021 W·m⁻¹·K⁻¹) and pollutant adsorption capacity (45–67 times its weight). This research offers a new approach for developing high-strength, multifunctional SiC aerogels.