Macroscopic Electromagnetic Cooperative Network-Enhanced MXene/Ni Chains Aerogel-Based Microwave Absorber with Ultra-Low Matching Thickness

Abstract

Electromagnetic cooperative strategy has been presented as a mainstream approach that can effectively optimize the matching thickness of dielectric loss dominant system. However, it is still challenging for dielectric–magnetic loss coexisting-type absorber to develop electromagnetic wave (EMW) performance with ultra-low matching thickness (≤ 1 mm). Breaking the limitation of traditional electromagnetic response at microscopic/mesoscopic scale, a ficus microcarpa-like magnetic aerogel with macroscopical electromagnetic cooperative effect was fabricated through highly oriented self-assembly engineering. The highly oriented Ni chains with unique macroscopic morphology (~ 1 cm in length) were achieved via a special magnetic field-induced growth. Strong magnetic coupling was observed in the Ni chains confirmed by the micromagnetic simulation. The deductive calculation validates that maintaining high value of electromagnetic parameters at high frequencies is the prerequisites of ultrathin absorber. The electromagnetic cooperative networks with uninterrupted and dual pathways spread through the entire aerogel skeleton, resulting in the impressive permittivity even at high frequencies. Consequently, the aerogel exhibits a remarkable EMW performance at an ultrathin thickness of 1 mm. Thus, based on the modulation of electromagnetic parameters, this work proposed a macroscopic ordered structure with the electromagnetic cooperative effect useful to develop a suitable strategy for achieving ultrathin EMW absorbers.

3D Printed Integrated Gradient-Conductive MXene/CNT/Polyimide Aerogel Frames for Electromagnetic Interference Shielding with Ultra-Low Reflection

“…In recent years, lightweight aerogels with high porosity are considered as promising materials for EMI shielding [ 4 , 12 ]. Benefit to the three-dimensional (3D) porous structure of aerogel, the incident electromagnetic waves can be multiple reflected/scattered and lost in the porous structure, thus enhancing the EMI shielding performance, especially its electromagnetic wave absorption ability [ 13 , 14 ]. For instance, Zhao et al [ 15 ] reported transition-metal carbides (MXenes)/graphene oxide (GO) hybrid aerogel with aligned cellular microstructure and high conductivity (1085 S m −1 ), which effectively performs electron transfer and microwave attenuation exhibiting high EMI shielding effectiveness (EMI SE = 50 dB in the X band).…”

Lightweight Honeycomb rGO/Ti3C2Tx MXene Aerogel without Magnetic Metals toward Efficient Electromagnetic Wave Absorption Performance

“…The RL value of EMW-absorbing materials can be calculated according to the generalized transmission line theory, and the formula is as follows , RL = 20 0.25em log 10 | Z in − Z 0 Z in + Z 0 | Z normali normaln = Z 0 μ r ε r 0.25em tanh [ j true( 2 π italicfd c true) μ r ε r ] in which μ r and ε r are the permeability and complex permittivity, respectively; Z 0 represents the impedance of free space; Z in can be denoted as the input characteristic impedance; f is the given frequency; c is the light speed in vacuum; and d refers to the thickness of the sample.…”

“…The RL value of EMW-absorbing materials can be calculated according to the generalized transmission line theory, and the formula is as follows 21,38…”

“…20 Simultaneously, plenty of interfaces gained during the process can bring about more interfacial polarizations, which is beneficial for nonmagnetic EMW-absorbing materials to balance the impedance matching and improve the EMW absorption property. Although several studies have constructed a series of carbon-based aerogel structures, additional templates including biological basis 21 and complex synthesis steps like reduction of hydrazine hydrate 16 are often employed. Herein, it is urgently needed to synthesize nonmagnetic carbon-based aerogel materials through a green and convenient way.…”

Fabrication of an Ultralight Ni-MOF-rGO Aerogel with Both Dielectric and Magnetic Performances for Enhanced Microwave Absorption: Microspheres with Hollow Structure Grow onto the GO Nanosheets

“…Generally, EMW absorption materials include dielectric loss materials and magnetic loss materials. − Dielectric loss materials have been of widespread concern in the past decades, − such as graphene and its derivatives and MXenes. − These kinds of materials have the merits of superior conduction property, high specific surface area, and multilayered structure. However, they have some shortages too.…”