Thermally tailoring magnetic molecular sponges through self-propagating combustion to tune magnetic-dielectric synergy toward high-efficiency microwave absorption and attenuation

Tailoring microstructures and compositions can flexibly tune the electromagnetic properties of materials to realize high-efficiency microwave absorption and microwave attenuation. Herein, through an in site transformation process based on combustion, three-dimensional (3D) magnetic molecular sponge with the ultrahigh porous micro/nanostructure and uniformly dispersed CoFe units (denoted as CoFe@PCS) was successfully fabricated through self-propagating combustion from the energetic metal organic framework. Its unique framework microstructure and integrated magnetic-dielectric components give it efficiently microwave absorption. The minimum reflection loss of the CoFe@PCS reaches as - 70.10 dB at the thickness of 2.57 mm with a wide effective absorption bandwidth of 8.64 GHz. More importantly, loss mechanism and energy dissipation inside magnetic sponge are deeply dissected to reveal the relaxation-dominated dielectric loss and dielectric-magnetic synergy. This work offers an ingenious approach for the target design and fabrication of high-performance absorbers.