Attenuation of electromagnetic microwaves by a sandwich-like hybrid nanocomposite of reduced graphene oxide and amine-functionalized magnetic mesoporous silica.

• The sandwich-like structure of rGO/Fe 3 O 4 @mSiO 2 nanocomposites (rGAMS) was synthesized via amidation reaction. • The sandwich-like structure of rGAMS resulted in a nanocomposite with excellent electromagnetic absorbing ability. • It enhanced the internal reflection within the structure of the composite to dissipate microwave radiation. • This work has opened the application of multifunctional porous materials in microwave shielding applications. A hybrid composite with a sandwich-like structure constructed from reduced graphene oxide (rGO) and magnetic Fe 3 O 4 particles coated mesoporous SiO 2 (Fe 3 O 4 @mSiO 2) is reported. For better adhesion of Fe 3 O 4 @mSiO 2 on the rGO sheets, the surface of the Fe 3 O 4 @mSiO 2 was modified with amonopropyltriethoxysilane to form amine-functionalized magnetic mesoporous silica (AMS). The anchoring of AMS particles on the surface of rGO in the resulting reduced graphene oxide/amine-functionalized magnetic mesoporous silica (rGAMS) hybrid greatly improved exfoliation of the rGO sheets. The as-synthesized rGAMS readily absorbed microwave radiation in epoxy composites. An rGAMS absorber with 10 wt% filler loading had an effective absorption bandwidth of 9.8 GHz in the frequency from 8.2 to 18 GHz, and the minimum reflection loss was -49.4 dB at 13.4 GHz. The adhesion of AMS particles not only induced a high specific surface area, but also acted as loci for microwave entrapment due to magnetic loss caused by their intrinsic porosity. [ABSTRACT FROM AUTHOR]