MIL-88B (Fe) driven Fe/Fe3C encapsulated in high-crystalline carbon for high-efficient microwave absorption and electromagnetic interference shielding

Abstract

Dual-functional magnetic/dielectric Fe/Fe3C@C composites were fabricated by pyrolysis of MIL-88B (Fe) in an Ar atmosphere, which was used for microwave absorption and electromagnetic interference (EMI) shielding. The Fe/Fe3C nanocrystals were completely encapsulated in crystalline carbon, which can improve oxidation resistance capacity. Owing to remarkable impedance matching and strong attenuation constants, the Fe/Fe3C@C composites show an optimal reflection loss (RL) value of −56.4 dB at 14.0 GHz and a broad effective absorption bandwidth (RL ⩽ −10 dB) of 4.8 GHz when the filling ratio and absorber thickness are only 20 wt% and 1.9 mm, respectively. Resulting from the high conductivity of crystalline carbon, magnetic loss of Fe/Fe3C, and core–shell structure, the Fe/Fe3C@C composites also show remarkable EMI shielding properties at the X band, which are enhanced by increasing the filling ratio of the Fe/Fe3C@C composites. When the filling ratio is 50 wt%, the EMI shielding efficiency can reach 35 dB. This work suggests that magnetic/dielectric Fe/Fe3C@C is a good candidate in microwave absorption and EMI shielding.