Ti₃C₂T_x/MoS₂ Self‐Rolling Rod‐Based Foam Boosts Interfacial Polarization for Electromagnetic Wave Absorption

Abstract

Heterogeneous interface design to boost interfacial polarization has become a feasible way to realize high electromagnetic wave absorbing (EMA) performance of dielectric materials. However, interfacial polarization in simple structures such as particles, rods, and flakes is weak and usually plays a secondary role. In order to enhance the interfacial polarization and simultaneously reduce the electronic conductivity to avoid reflection of electromagnetic wave, a more rational geometric structure for dielectric materials is desired. Herein, a Ti 3 C 2 T x /MoS 2 self-rolling rod-based foam is proposed to realize excellent interfacial polarization and achieve high EMA performance at ultralow density. Different surface tensions of Ti 3 C 2 T x and ammonium tetrathiomolybdate are utilized to induce the self-rolling of Ti 3 C 2 T x sheets. The rods with a high aspect ratio not only remarkably improve the polarization loss but also are beneficial to the construction of Ti 3 C 2 T x /MoS 2 foam, leading to enhanced EMA capability. As a result, the effective absorption bandwidth of Ti 3 C 2 T x /MoS 2 foam covers the whole X band (8.2-12.4 GHz) with a density of only 0.009 g cm −3 , at a thickness of 3.3 mm. The advantages of rod structures are verified through simulations in the CST microwave studio. This work inspires the rational geometric design of micro/nanostructures for new-generation EMA materials.

Electrostatic Adsorption Enables Layer Stacking Thickness‐Dependent Hollow Ti3C2Tx MXene Bowls for Superior Electromagnetic Wave Absorption

“…After attachment with MXenes, the surface tension of the PS microspheres would induce bending of the MXenes. [28] Correspondingly, the MXene nanosheets wrapped around the surface of the PS microspheres, forming MXene@PS hybrids (Figure 1b,c), driven by the electrostatic adsorption between the negative MXene nanosheets (−18.6 mV at pH = 3) and positive PS microspheres (+16.2 mV at pH = 3), [27,29,30] as shown in Figure S3, Supporting Information.…”

“…As shown in Figure S19d, Supporting Information, polarization loss of the pristine MXene nanosheets was limited due to the presence of sheet structures that cannot increase interfaces between two sheets. [28] DFT calculations of the hollow MXene bowls were used to quantitatively analyze the effects of the layer stacking thickness and interlayer spacing on the dielectric loss; the calculation models are shown in Figure S22a-d, Supporting Information. The DOS of the Ti and C atoms from the hollow MXene bowls was calculated.…”

A Lightweight, Elastic, and Thermally Insulating Stealth Foam With High Infrared‐Radar Compatibility

“…According to the transmission line theory, the input impedance (Z in ) represents the impedance value at the air-material interface, which can be calculated by the following formula using the frequencydependent complex permeability 𝜇 r and permittivity 𝜖 r : [48] Above, Z M is the characteristic impedance of the microwave absorbing materials, Z 0 is a fixed constant 120 𝜋 (≈377) Ω standing for the intrinsic impedance of free space, d means thickness of the microwave absorber, and c signifies the speed of light. Based on the metal back plane model, the microwave-absorption performance of the bulk PPM/paraffin composites could be evaluated via reflection loss (RL) values: [49,50]…”

“…Above, Z M is the characteristic impedance of the microwave absorbing materials, Z 0 is a fixed constant 120 π (≈377) Ω standing for the intrinsic impedance of free space, d means thickness of the microwave absorber, and c signifies the speed of light. Based on the metal back plane model, the microwave‐absorption performance of the bulk PPM/paraffin composites could be evaluated via reflection loss (RL) values: [ 49 , 50 ] …”

Hydro/Organo/Ionogels: “Controllable” Electromagnetic Wave Absorbers

“…To prove this conclusion, their polarization loss and conductive loss are calculated based on the Debye theory (Figure 3d). [34] Computational results demonstrate that for both hydrogels and organogels, polarization loss plays a dominant role while conduction loss contributes little. For ionogels, conduction loss dominates with a small proportion of polarization loss.…”