Efficient and Lightweight Electromagnetic Wave Absorber Derived from Metal Organic Framework-Encapsulated Cobalt Nanoparticles

Abstract

Porous-carbon-based nanocomposites are gaining tremendous interest because of good compatibility, lightweight, and strong electromagnetic wave absorption. However, it is still a great challenge to design and synthesize porous-carbon-based composites with strong absorption capability and broad frequency bandwidth. Herein, a facile and effective method was developed to synthesize Co magnetic nanoparticles/metal organic framework (MOF) (Co NPs/ZIF-67) nanocomposites. Co NPs/porous C composites were subsequently obtained by annealing Co NPs/ZIF-67 nanocomposites at different temperatures under an inert atmosphere. The carbonized nanocomposites showed highly efficient electromagnetic wave absorption capability. Specifically, the optimal composite (i.e., Co/C-700) possessed a maximum reflection loss (RL) value of -30.31 dB at 11.03 GHz with an effective absorption bandwidth (RL ≤ -10 dB) of 4.93 GHz. The electromagnetic parameters and the absorption performance of the composites are readily tunable by adjusting the carbonization temperature and the concentration of Co NPs in the composites. Because of the combination of good impedance matching, dual-loss mechanism, and the synergistic effect between Co NPs and porous carbon composites, these Co NPs/MOF-derived composites are attractive candidates for electromagnetic wave absorbers.

An Efficient Co/C Microwave Absorber with Tunable Co Nanoparticles Derived from a ZnCo Bimetallic Zeolitic Imidazolate Framework

“…Hence, we compared the impedance matching of the four composites at a representative thickness of 2 mm. Generally, ideal impedance matching requires the | Z in / Z 0 | value to equal 1.0, which implies the zero‐reflection of incident EM wave at the front surface of absorber . As seen in Figure b, the | Z in / Z 0 | curve of Co50/C composite is close to 1.0 in a wider frequency range compared with other samples, which implies its better impedance matching.…”

Nickel Carbon Composite With Carbon Nanotubes for Efficient Electromagnetic Wave Absorption

“…One semicircle appears in the ε'-ε″ diagram corresponds to a polarization relaxation process, The magnetic loss is also important for absorbing the EM waves. Generally, the magnetic loss mainly comes from domain wall resonance, hysteresis loss, and eddy current loss [45]. Domain wall resonance loss and hysteresis loss always occur at low frequency [46].…”

Recent Development in Fabrication of Co Nanostructures and Their Carbon Nanocomposites for Electromagnetic Wave Absorption

“…[27] Recently, metalorganic-frameworks (MOFs) derived porous carbon/Co nanocomposites derived through pyrolysis of ZIF-67 have attracted great attentions and excellent EM wave absorption was reported. [28][29][30] Considering of these new developments, it is quite necessary to provide a critical assessment and future applications of Co-based materials as EM wave absorbers. To the best of our knowledge, reviews concerned about development of Co-based absorbers haven't been outlined.…”

“…The highly efficient EMW absorption was attribute to the synergy of magnetic loss from Co core and high dielectric loss of carbon shell along with the interface polarization due to the core-shell structure. In Wang's report, the Co NPs/porous carbon composites derived from MOFs possessed strong RL of -30.31 dB at 11.03 GHz and broad fe of 4.93 GHz was observed 28. The EM parameters and absorbing performances can be adjusted effectively through controlling the…”