Laminated and Two-Dimensional Carbon-Supported Microwave Absorbers Derived from MXenes

Abstract

Microwave absorbers with layered structures that can provide abundant interfaces are highly desirable for enhancing electromagnetic absorbing capability and decreasing the thickness. The atomically thin layers of two-dimensional (2D) transition-metal carbides (MXenes) make them a convenient precursor for synthesis of other 2D and layered structures. Here, laminated carbon/TiO hybrid materials composed of well-aligned 2D carbon sheets with embedded TiO nanoparticles were synthesized and showed excellent microwave absorption. Disordered 2D carbon layers with an unusual structure were obtained by annealing multilayer TiC MXene in a CO atmosphere. The minimum reflection coefficient of laminated carbon/TiO composites reaches -36 dB, and the effective absorption bandwidth ranges from 3.6 to 18 GHz with the tunable thickness from 1.7 to 5 mm. The effective absorption bandwidth covers the whole Ku band (12.4-18 GHz) when the thickness of carbon/TiO/paraffin composite is 1.7 mm. This study is expected to pave the way to the synthesis of carbon-supported absorbing materials using a large family of 2D carbides.

Multifunctional, Superelastic, and Lightweight MXene/Polyimide Aerogels

“…The magnetic permeability is omitted because both MXene and PI are nonmagnetic, and thus the MXene materials attenuate microwave mainly by the dipolar polarization induced by the surface terminations, localized defects, and dangling bonds, which has been systematically studied by Han et al Interestingly, the lightweight aerogel has a large dielectric loss tangent (tan δ e = ε″/ε′) of 0.39, which is comparable to the reported powdery MXene‐based materials with much higher loadings. [24a,b,25] Generally, the frequency bandwidth of reflection loss ≤−10 dB is considered as the effective absorption bandwidth (EAB). For the MXene/PI aerogel (8.9 mg cm −3 , ≈4.0 S m −1 ), a maximum reflection loss of −45.4 dB is achieved at 9.59 GHz (3 mm) and the EAB reaches up to 3.7 GHz (8.3–12.0 GHz), which almost cover the whole X‐band (Figure c).…”

Development of a hollow carbon sphere absorber displaying the multiple-reflection effect to attenuate electromagnetic waves

“…5 Overall, the conductivity of amorphous carbon is moderate as compared to other carbon materials like graphene, graphite etc. [6][7][8] Based on this consideration, amorphous carbon has a huge potential for combating the serious electromagnetic interference issue (EMI) if serving as an electromagnetic absorber. 9 In recent years, the rapid development of electronic, wireless communication techniques has resulted in increasing levels of electromagnetic pollution.…”

Enhanced Terahertz Shielding of MXenes with Nano‐Metamaterials

“…Recently, 2D transition metal carbide (MXene) has shown excellent shielding performance in the microwave regime . Among all, a thin film of Ti 3 C 2 T x MXenes (≈1.5 µm) can block 99.99% EM waves showing the highest EMI shielding efficiency (EMI SE) for materials of comparable thicknesses . Han et al reported a composite of Ti 3 C 2 T x in wax which delivers an EMI SE value of 76.1 dB with a thickness of only 1 mm .…”