Fabrication of core-shell structure NiFe2O4@SiO2 decorated nitrogen-doped graphene composite aerogels towards excellent electromagnetic absorption in the Ku band

Abstract

The fabrication of advanced electromagnetic wave absorbents with wide bandwidth, robust absorption and small filling ratio remains a great challenge. In this work, the ternary composite aerogel of nitrogen-doped reduced graphene oxide/nickel ferrite@silicon dioxide modified by amino groups (NRGO/NiFe2O4@m-SiO2) was synthesized via the three-step route of solvothermal synthesis, Stöber method and hydrothermal self-assembly. Microscopic morphology characterization results indicated that the acquired binary and ternary magnetic composite aerogels exhibited a special three-dimensional porous network architecture. Moreover, the electromagnetic absorbing capacity of NRGO/NiFe2O4 composite aerogel could be obviously enhanced by coating SiO2 and modifying amino groups on the surfaces of SiO2. Remarkably, the as-fabricated NRGO/NiFe2O4@m-SiO2 composite aerogel possessed the broadest effective absorption bandwidth of 7.04 GHz (10.96–18.0 GHz) and robust absorbing intensity of −30.8 dB at 2.1 mm under a small filling ratio of 12.5 wt%. It was worth mentioning that the optimal minimum reflection loss could reach −56.0 dB when the matching thickness was increased to 3.4 mm. Besides, a minimum radar cross section value of −51.1 dB m2 could be achieved in the far-filed condition. The special porous network structure and magnetodielectric synergy in the ternary composite aerogel optimized the electromagnetic impedance, and notably enhanced the electromagnetic absorbing capacity. It was believed that this study would provide a novel approach for the construction of highly efficient carbon-based electromagnetic wave absorbers.