Ultrathin Self‐Assembly MXene@flake Carbonyl Iron Composites with Efficient Microwave Absorption at Elevated Temperatures

Abstract

waves produced by electronic devices, speed up information transmission while creating a lot of pollution, providing more and more harm to human beings. Thus, the investigation on lightweight and high efficiency EM absorbing materials and devices is widely developed. However, with the emergence of new application, such as 5G electronic devices, EM absorption materials are expected to show stable and efficient performance in thermal environments. There are rarely reports about EM absorbers to meet harsh requirement of thermal environments. The investigation of highly efficient, lightweight EM absorption materials at elevated temperature is still a great challenge.Recently, 2D materials apply to EM absorbers have attracted much attention. For example, graphene have been widely applied in EM absorbing materials due to high specific surface area, light weight, and excellent polarization loss, which enhance polarization to attenuate EM waves. [1] In addition, a class of metal carbide and metal nitride materials (MXene) as a new candidate in 2D materials has been extensively used in fields of EM absorbing and electromagnetic interference (EMI) shielding due to its excellent metal-like conductivity, abundant active surface functional groups, and good machine performance. [2][3][4][5] Ti 3 C 2 T x (T x represents OH, O, or F), a typical MXene material, can be used as a potential EMI material based on high conductivity, which has EMI effectiveness of 92 dB at 45 µm. [3] The metal-like conductivity of Ti 3 C 2 T x causes interface impedance mismatch resulting in poor EM absorbing performance, though there is part of the EM wave attenuation due to polarization and conductivity loss. It is considered that combination of dielectric and magnetic loss materials for high-efficiency EM wave absorbers as an effective strategy, which not only contributes to interface impedance matching of the material and EM waves, but also broadens the EM waves absorption mechanism. [6,7] Magnetic material-carbonyl iron powder, compared with ferrites and ferroalloys such as Fe 3 O 4 , [8] FeCo, [9] has the advantage of strong magnetic loss in the gigahertz frequency band, high Curie temperature, and low cost. [10] In addition, the flake carbonyl iron (FCI) possesses high anisotropy and its magnetic permeability is further enhanced. [11] It has been proven to exhibit the potential to be broadband andThe exploration for the potential lightweight and high efficiency microwave absorbers with thermal stability is a great challenge for researchers. More importantly, the electromagnetic parameters of absorbers at elevated temperatures are seldom studied. In this work, sandwich MXene-Ti 3 C 2 T x @flake carbonyl iron (MF) composites with tunable and efficient microwave absorption at elevated temperatures are successfully fabricated by an electrostatic selfassembly method. Both the complex permittivity and permeability of the MF are strongly temperature dependent in the temperature range of 298-473 K and X band (8.2-12.4 GHz). The efficient microwave ab...

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“…To achieve high-efficiency EM absorption, both impedance matching and excellent microwave attenuation ability are necessary . Hereby, the reflection coefficient (RC) is the most significant and prominent parameter to evaluate the EM wave absorption ability.…”

“…To achieve high-efficiency EM absorption, both impedance matching and excellent microwave attenuation ability are necessary. 60 Hereby, the reflection coefficient (RC) is the most significant and prominent parameter to evaluate the EM wave absorption ability. When the RC value is lower than −10 dB, 90% of the incident wave is attenuated, which is derived from the transmission line theoretical model according to eqs 1 and 2…”

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