Ultralight and efficient microwave absorption of SiC/SiO₂ ceramic aerogels derived from biomass

Rational multicomponent regulation and microstructure design have proven to be effective strategies for achieving high performance electromagnetic wave (EMW) absorbers. Herein, the ultralight hierarchically porous SiC/SiO₂ aerogels (HPSA) were successfully synthesized by an ingenious one-step method to achieve carbonization and carbothermal reduction. The composition of the HPSA and the quantity of SiC/SiO₂ fibers grown by in situ reaction can be controlled by adjusting the amount of silicon source introduced. The results indicate that the composition of HPSA and the quantity of fibers have a significant effect on the EMW absorption properties. When the introduced silicon source concentration was 0.7 mol/L, the HPSA exhibited excellent EMW absorption performance, with a minimum reflection loss (RL_min) of -55.01 dB at 6.00 GHz and a maximum effective absorption bandwidth (EAB_max) of 6.16 GHz. The highly interconnected porous SiC/SiO₂ skeleton structure significantly contributes to the multiple reflection-absorption effect of EMW and provides available pathways for electron conduction losses. The in situ reaction generates SiC/SiO₂ fibers with a large number of stacking faults and heterojunctions, which further promote the dissipation of EMW. In addition, the maximum radar cross section of HPSA under far-field conditions is reduced to 20.21 dB m² compared to the PEC conductive layer, which implies a much lower probability of detection by radar. In brief, this work provides a reference for the use of highly efficient EMW absorbers and electromagnetic stealth materials.