nondestructive detection, [2] material identification, [3] biomedical sensing, [4] to the emerging sixth generation (6G) communications, [5] in which THz absorbers with high absorption intensity (>99%) in a large qualified bandwidth are urgently demanded. THz absorber can be widely used in THz emitting/detecting antennas to reduce the sidelobe radiation or any undesirable radiation, or in the whole THz systems to suppress the electromagnetic interference (EMI). [6,7] Another potential use is for radar cross-section (RCS) reduction, which can reduce radar echo to achieve a greater element of stealth. [8] Considering that THz imaging system has already been commercialized, [9,10] THz communication have been officially designated for 6G network, [11-13] and even the prototype of THz radar have been demonstrated for concealed weapon detection, [14-16] there is being an urgent and huge demand of high-intensity absorption, broadband, and low cost THz absorber in both military and civilian aspects. Generally, condensed materials with higher conductivity inherently have higher electromagnetic (EM) loss, which, however, does not guarantee a stronger absorption because higher conductivity in turn leads to stronger reflection at the surface of material. When EM wave radiates from free space to a condensed material, the reflection from the surface is nearly inevitable to occur unless the impedance matching is achieved,

Electromagnetic interference (EMI) shielding materials have received considerable attention in recent years. The EMI shielding effectiveness (SE) of materials depends on not only their composition but also their microstructures. Among various microstructure prototypes, porous structures provide the advantages of low density and high terahertz wave absorption. In this study, by using carbonised wood (CW) as a template, 1-mm-thick MAX@CW composites (Ti2AlC@CW, V2AlC@CW, and Cr2AlC@CW) with a porous structure were fabricated through the molten salt method. The MAX@CW composites led to the formation of a conductive network and multilayer interface, which resulted in improved EMI SE. The average EMI SE values of the three MAX@CW composites were > 45 dB in the frequency of 0.6–1.6 THz. Among the composites, V2AlC@CW exhibited the highest average EMI SE of 55 dB.

Porous polymer‐based Terahertz (THz) absorbers possess strong absorption with broadband, lightweight, and flexible features. Thus these are widely desired in THz electromagnetic shielding, radar‐cross‐section reduction, radiometer calibration, etc. However, the harsh environment of humidity, corrosiveness, and dustiness undermines the performance and service lifetime of the porous absorbers. Here, based on Ti3C2Tx MXene sponge composite foam (MSF), a superhydrophobic broadband THz absorber on a large pore‐size porous architecture by a joint hydrophobic strategy is realized. Results show that the apparent contact angles and roll‐off angles of the modified MSF reached 159.0° and 7.6°, while maintaining an ultra‐high absorption rate of 99.6% in the frequency range of 0.3–1.2 THz. Furthermore, the special Micro‐Nano hierarchical structures render the absorber a strong bounce‐off ability to the droplets of an aqueous solution. These water‐repellent properties endow the absorber the versatility of self‐cleaning and anti‐corrosion, thus can be widely applied in many scenarios including THz remote sensing, communication, and security screening as well.

Electromagnetic interference (EMI) shielding materials have received great interests in recent years. The EMI shielding effectiveness (SE) of materials not only depends on their composition, but also is influenced by their microstructures. Among various microstructure prototypes, porous structure has special advantage of low density and high electromagnetic wave reflections ability. Herein, a MAX@CW composite (Ti2AlC@CW, V2AlC@CW, Cr2AlC@CW) with porous structure is fabricated through a molten salt method by using carbonized wood (CW) as template. The MAX@CW forms conductive network constructions and rich interface that can further improve the EMI shielding effectiveness. The average EMI shielding effectiveness of the three kinds of MAX@CW with the thickness of 1 mm are higher than 45 dB in the frequency range of 0.6 ~ 1.6 THz. Among them, V2AlC@CW show the best EMI shielding effectiveness with the average value of 55 dB.