Ultra-broadband microwave absorption performance of multi-scale designed Fe3O4@NiCo2O4/PANI/NRGO aerogels

Abstract

In this study, we developed a microstructure design and an appropriate multicomponent strategy to optimize a microwave absorber: Fe₃O₄@NiCo₂O₄/PANI/NRGO aerogels. We synthesized Fe₃O₄ hollow spheres, Fe₃O₄@NiCo₂O₄, Fe₃O₄@NiCo₂O₄/PANI, and finally, Fe₃O₄@NiCo₂O₄/PANI/NRGO aerogels using hydrothermal and in situ polymerization methods. The maximum reflection loss of the aerogels can reach −41.8 dB at 16.7 GHz with a thickness of only 2.0 mm; the bandwidth, with absorption above 90%, is 13.3 GHz (4.7–18 GHz for matching thicknesses of 1.6–5.0 mm). The maximum reflection loss of the Fe₃O₄@NiCo₂O₄ sample reaches −50.9 dB at 5.7 GHz with a matching thickness of 3.0 mm; the bandwidth with a reflection loss less than −10 dB is 15.0 GHz (3–18 GHz for 1.0–5.0 mm matching thicknesses). The enhanced electromagnetic absorption performance is due to synergetic magnetic loss, dielectric loss, and conduction loss in the porous multi-scaled structure with a hollow interior, including various rich interfaces provided by the distribution of different components in the heterostructures. Our results provide a new approach for designing and constructing excellent microwave-absorbing materials for practical applications.