Synthesis of the SiO2@C composites with high-performance electromagnetic wave absorption

Abstract

A series of core-shell SiO2@C microspheres with different size of SiO2 microspheres and thickness of conductive carbon black (CB) were prepared via carbothermal reduction method. The samples were characterized by SEM, TEM, XRD, XPS and Raman spectroscopy analyses. When the size of SiO2 microspheres or CB thickness was changed, the as-synthesized SiO2@C composites possessed diverse reflection loss (RL). Among, the electromagnetic wave (EMW) absorption performance of S-2 composite was optimal and its minimum reflection loss (RLmin) was up to −39.7 dB at the thickness of 3.8 mm and the effective bandwidth (RL ≤ −10 dB, 90% absorption) covered 1.3 GHz. Hence, it is the size of SiO2 microspheres and CB content that can tune the EMW absorption performance of the SiO2@C composites, which makes SiO2@C composites rather promising EMW absorption materials.