Thermal conversion of an Fe₃O₄@metal–organic framework: a new method for an efficient Fe–Co/nanoporous carbon microwave absorbing material

Abstract

A novel FeCo nanoparticle embedded nanoporous carbon composite (Fe-Co/NPC) was synthesized via in situ carbonization of dehydro-ascorbic acid (DHAA) coated Fe3O4 nanoparticles encapsulated in a metal-organic framework (zeolitic imidazolate framework-67, ZIF-67). The molar ratio of Fe/Co significantly depends on the encapsulated content of Fe3O4 in ZIF-67. The composites filled with 50 wt% of the Fe-Co/NPC-2.0 samples in paraffin show a maximum reflection loss (RL) of -21.7 dB at a thickness of 1.2 mm; in addition, a broad absorption bandwidth for RL < -10 dB which covers from 12.2 to 18 GHz can be obtained, and its minimum reflection loss and bandwidth (RL values exceeding -10 dB) are far greater than those of commercial carbonyl iron powder under a very low thickness (1-1.5 mm). This study not only provides a good reference for future preparation of carbon-based lightweight microwave absorbing materials but also broadens the application of such kinds of metal-organic frameworks.

Broadening Electromagnetic Absorption Bandwidth: Design from Microscopic Dielectric‐Magnetic Coupled Absorbers to Macroscopic Patterns

“…Furthermore, alternative methods including using frequency selective radar absorbing materials, graded-dielectric multilayer, and employment of concise design of the microscopic structures of the fillers are promising methods for achieving high-performance microwave absorption materials and composites. [41][42][43][44][45][46][47] Moreover, the mechanical properties and the significant factors that impact the performance should be concerned. [48][49][50][51][52][53] Figure 12 displays the effective absorption bandwidth of the materials and structures.…”

Enhanced high-frequency absorption of anisotropic Fe3O4/graphene nanocomposites

“…As a wave absorption material, Fe 3 O 4 have been studied extensively for its excellent absorption properties by virtue of strong permeability and relative high resistivity. Many Fe 3 O 4 composites also have been reported in recent years: Fe 3 O 4 @ZnO sphere decorated graphene12, Fe 3 O 4 /TiO 2 core-shell nanotubes13, Fe 3 O 4 @TiO 2 yolk–shell microspheres14, fluorinated polybenzobisoxazole/silica-coated magnetic Fe 3 O 4 nanocomposities15, Fe 3 O 4 /SiO 2 nanorods16, graphene@Fe 3 O 4 nanocluster@carbon@MnO 2 nanosheet array composites17, superparamgnetic Fe 3 O 4 nanocrystals18, Fe 3 O 4 @C core-shell nanotubes19, Fe 3 O 4 @metal–organic framework20, 3D Fe 3 O 4 nanocrystals decorating carbon nanotubes21.…”

Fe3O4@MOF Magnetic Nanocomposites: Synthesis and Applications

“…Zhang and co‐workers in 2015 reported a method to synthesize well dispersed magnetic Fe‐Co alloy NPs embedded in nanoporous carbon (Fe‐Co/NPC) by thermal decomposition of a modified ZIF via encapsulating different content of ultra‐small iron oxide (Fe 3 O 4 ) nanoparticles (IONPs), which coated by dehydro‐ascorbic acid (DHAA) within the frameworks of ZIF‐67 . The magnetization properties of the IONP@ZIF‐67‐ x composite was measured and showed in Figure .…”