Large-scale and low-cost synthesis of in situ generated SiC/C nano-composites from rice husks for advanced electromagnetic wave absorption applications

Electromagnetic interference and pollution are becoming more prevalent due to rapid development and wide adoption of information technology. As promising microwave absorbents, SiC nanomaterials have aroused extensive attention due to the good absorption and tunable electrical properties. However, practical implementation is hindered by limited and simple dipolar polarization and complicated fabrication process. Herein, in situ generated SiC/C nanocomposites are designed and prepared from natural rice husks via magnesiothermic reduction. The in situ generated SiC nanoparticles are anchored inherently within the connecting carbon matrix yielding an enriched SiC-C interface. The carbon concentration can be easily adjusted by adding different amount of RHs-derived nano SiO₂ during the reaction in order that the optimal impedance matching and attenuation capability can be achieved. Consequently, the minimum reflection loss of −27.78 dB was obtained at 10.1 GHz with the thickness of 2.4 mm, while the effective absorption bandwidth is close to 3.9 GHz with the thickness of 1.6 mm. Considering the low-cost and large-scale advantages of the preparation protocol and excellent EM absorption properties, the fabrication strategy and in situ generated SiC/C materials have large potential for EM wave absorption applications.