Developing ultrabroad radar-infrared compatible stealth materials has turned into a research hotspot, which is still a problem to be solved. Herein, the copper sulfide wrapped by reduced graphene oxide to obtain three-dimensional (3D) porous network composite aerogels (CuS@rGO) were synthesized via thermal reduction ways (hydrothermal, ascorbic acid reduction) and freeze-drying strategy. It was discovered that the phase components (rGO and CuS phases) and micro/nano structure (microporous and nanosheet) were well-modified by modulating the additive amounts of CuS and changing the reduction ways, which resulted in the variation of the pore structure, defects, complex permittivity, microwave absorption, radar cross section (RCS) reduction value and infrared (IR) emissivity. Notably, the obtained CuS@rGO aerogels with a single dielectric loss type can achieve an ultrabroad bandwidth of 8.44 GHz at 2.8 mm with the low filler content of 6 wt% by a hydrothermal method. Besides, the composite aerogel via the ascorbic acid reduction realizes the minimum reflection loss (RLmin) of − 60.3 dB with the lower filler content of 2 wt%. The RCS reduction value can reach 53.3 dB m2, which effectively reduces the probability of the target being detected by the radar detector. Furthermore, the laminated porous architecture and multicomponent endowed composite aerogels with thermal insulation and IR stealth versatility. Thus, this work offers a facile method to design and develop porous rGO-based composite aerogel absorbers with radar-IR compatible stealth.

With the rapid development of 5th Generation Mobile Communication Technology (5G), late-model electromagnetic wave absorbing and shielding (EMAS) materials have proven to be the research emphasis of electromagnetic (EM) wave shelter. Great efforts have been made to optimize EMAS functional materials for diverse EM wavebands. [1] Each range of EM wave bands has a specific application in communication, electrical engineering, or information transmission. [2] For instance, ultrahigh frequency (UHF) EM wave of 0.3 < f < 3 GHz, also known as P/L/S or B/C/D/E band, is applied to television radar air navigation and mobile communication as well as microwave relay systems; the superhigh frequency (SHF) EM wave of 3 < f < 30 GHz, including S/C/X/Ku/K/ Ka-band or F/G/H/I/J/K band, is customarily adopted in digital telecommunication and satellite communication as well as waveguide communication. Moreover, EM waves in other frequency ranges, like terahertz wave and gamma ray, have been widely used in label-free DNA detection, high-temperature superconducting material research, radiographic testing, and even oncotherapy. In these cases, each specific application scenario requires specific EM waves in a specific frequency range, illustrating that EM wave clutters should be absorbed or otherwise shielded. Under these circumstances, developing novel and practical EMAS materials may meet the demands of EM wave science, especially in multifunctional fields.Traditional EMAS materials consist of resistance absorber, [3] dielectric absorber, [4] magnetic medium absorber, [5] and composites based on monomaterials as mentioned earlier, [6] including CuS, [7] MoSe 2 , [8] ferrites and alloys (Co x Fe 3Àx O 4 @C), [9] modified carbons (hollow carbon spheres), [10] etc. In the past decade, 2D transition metal carbides or nitrides, or MXenes, have been prefabricated and naturally applied to EMAS materials synthesis due to their outstanding EM wave loss capacity. [11] Many scholars have devoted themselves to MXene materials and structure design. The electrical conductivity of MXenes can reach 10 3 S cm À1 , leading to extraordinary EM wave shielding property. [12] Many reported MXene absorbers are monolayers, [13] whereas macrostructure design is introduced. Thus, macrodevices, like hollow MXene sphere foam, [14] are synthesized. It is

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It is still a formidable challenge to ameliorate the low-frequency electromagnetic property of conventional microwave-absorbing materials, which may be conquered by the coexistence of both strong dielectric and magnetic loss ability in low-frequency range and the perfect balance between complex permittivity and permeability with the help of structural design. Herein, by virtue of appropriate composition and structure of Co[HCOO]·dimethylformamide parallelepipeds, one-dimensional spongelike metallic Co can be directly synthesized for the first time with strong magnetic loss in the low-frequency range. Furthermore, attenuation ability and impedance matching condition have been improved through the construction of interfacial structures between inner cobalt and surface carbon. With the structure of carbon changed from fragments to vertically aligned nanoflakes and eventually to a thick layer with extra fragments, the dielectric loss would be continuously strengthened, while the magnetic loss maintains well, followed by a remarkable decline. A perfect balance between dielectric and magnetic loss has been achieved by sample S-Co/C-0.3 with minimum reflection loss value around -20 dB and effective absorption frequency range about 3.84 GHz in the C band. Excellent microwave absorption performance can also be realized in X and Ku bands. In addition, as-prepared Co and Co/C composites can also be potentially applied in electromagnetic shielding. The findings may pave the way for the manufacture of metal-based metal-organic framework derivatives and the design of lightweight low-frequency electromagnetic materials.

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