Rapid one-pot synthesis of SiO2@SiO2/Carbon@Carbon core-shell composites with efficient microwave absorption in a short time

A carbon-silica nanomaterial for electromagnetic wave (EW) absorption was synthesized using a modified one-pot method. The unique hydrolysis-polymerization process forms a SiO2@SiO2/Carbon@Carbon core-shell structure. The growth process of the material was studied by transmission electron microscope (TEM) and thermogravimetric analysis (TGA). Nanoparticles were successfully synthesized with a core-shell structure after 6 h of reaction, and the composite material showed excellent EW absorption performance with a thickness of 3.8 mm. The minimum reflection loss (RLmin) was −56.3 dB, and the broadest effective absorption bandwidth (EAB) (RL ≤ 10 dB, 90% absorption) covered 5.15 GHz (12.48–17.63 GHz) with 1.8 mm of thickness. There is no significant difference in the EW absorption performance with increasing reaction time. Thus, this study provides a method for synthesizing EW-absorbing materials with shorter reaction time, simpler process, and excellent absorption properties, possibly a candidate for further application.