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 the SiC microtubule while simultaneously inducing the self-growth of SiC nanowires, achieving controllable hierarchical pore fabrication in a single step. Compared to conventional methods, this strategy significantly simplifies the fabrication process and enhances multifunctional performance through structural synergy. The unique microtube-nanowire heterostructure confers excellent electromagnetic wave absorption (minimum reflection loss 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 mechanical limits of conventional aerogels. Additionally, the aerogel exhibits superior 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.