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 could reach -41.8 dB at 16.7 GHz with a thickness of only 2.0 mm; the bandwidth with an absorption above 90% is determined to be 13.3 GHz (4.7–18 GHz for 1.6–5.0 mm matching thicknesses). The maximum reflection loss of the Fe3O4@NiCo2O4 sample could reach -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 determined to be 15.0 GHz (3–18 GHz for 1.0–5.0 mm matching thicknesses). The enhanced electromagnetic absorption performance is caused by synergetic magnetic loss, dielectric loss, and conduction loss in the porous multi-scaled structure with a hollow interior, rich with various interfaces provided by the distribution of different components in the heterostructures. Our results provide a new approach to designing and constructing excellent microwave-absorbing materials for practical applications.