Infrared (IR) stealth is essential not only in high technology and modern military but also in fundamental material science. However, effectively hiding targets and rendering them invisible to thermal infrared detectors have been great challenges in past decades. Herein, flexible, foldable, and robust Kevlar nanofiber aerogel (KNA) films with high porosity and specific surface area were fabricated first. The KNA films display excellent thermal insulation performance and can be employed to incorporate with phase-change materials (PCMs), such as polyethylene glycol, to fabricate KNA/PCM composite films. The KNA/PCM films with high thermal management capability and infrared emissivity comparable to that of various backgrounds demonstrate high performance in IR stealth in outdoor environments with solar illumination variations. To further realize hiding hot targets from IR detection, combined structures constituted of thermal insulation layers (KNA films) and ultralow IR transmittance layers (KNA/PCM) are proposed. A hot target covered with this combined structure becomes completely invisible in infrared images. Such KNA/PCM films and KNA–KNA/PCM combined structures hold great promise for broad applications in infrared thermal stealth.

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Novel TiO2/Ag/SnO2 composites were successfully prepared by a facile one-step reduction approach using stannous chloride as both SnO2 precursor and reducing agent. The Ag nanoparticles with sizes of 2.04–3.94 nm were located on TiO2 matrix and immobilized by the surrounded SnO2. The resulted TiO2/Ag/SnO2 nanocomposites were used as photocatalyst for photodegradation of methylene blue under visible light. The experimental results demonstrated that the visible light photocatalytic activity of the TiO2/Ag/SnO2 was significantly enhanced in comparison with the individual TiO2 or the binary composite (TiO2/Ag or TiO2/SnO2) and the degradation rate was up to about 9.5 times that of commercial TiO2. The photocatalytic activity of the TiO2/Ag/SnO2 composites could be well controlled by simply tuning the dosages of Ag precursor and the optimized activity of the composites was obtained when the dosage of Ag precursor was 2%. Moreover, the TiO2/Ag/SnO2 photocatalyst exhibited high stability for degradation of methylene blue even after four successive cycles.

The design and development of radar-−infrared compatible stealth materials are challenging in the field of broadband absorption due to the contradiction of stealth requirements and mechanisms in different frequency bands. However, hollow structures show great promise for multispectral stealth because they can lengthen the attenuation path of electromagnetic waves (EMWs) for microwave absorption, interrupt the continuity of heat-transport channels, and lower the thermal conductivity to realize infrared stealth. Here, a new morphological fabrication strategy has been developed to efficiently prepare compatible stealth nanomaterials. In a specific hydrothermal process, the confined growth of flake α-Fe 2 O 3 (f-Fe 2 O 3 ) outside of hollow mesoporous carbon spheres (HMCS) is achieved using NH 3 •H 2 O as a shape-controlled reagent. The introduction of f-Fe 2 O 3 helps to lower infrared emissivity and improve high-frequency impedance matching, which depends on the stable dielectric property of the specific flake shape. Moreover, the size of f-Fe 2 O 3 can be regulated by changing the constituent proportion in the hydrothermal suspension to obtain excellent performance. The minimum reflection loss (RL) of the HMCS@f-Fe 2 O 3 -6 composite is −34.16 dB at 2.4 mm, and the effective absorption bandwidth (EAB) reaches 4.8 GHz. Furthermore, the lowest emissivities of the HMCS@f-Fe 2 O 3 -6-20 wt %/polyetherimide (PEI) film in the 3−5 and 8−14 μm infrared wavebands are 0.212 and 0.508, respectively. These discoveries may pave the way for the development of radar−infrared compatible stealth materials from the perspective of microstructural design.

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Graphene aerogel fibers (GAFs) with low density, high specific surface area, and high porosity can be used as the host material to incorporate another component and thus form multifunctional fibers, which have potential applications in wearable devices, thermoregulating apparatus, sensors, and so forth. However, the intrinsically low electric conductivity of GAFs hampers them in the fields of electrothermal heating and electromagnetic interference (EMI) shielding. Herein, we report a new aerogel fiber composed by graphene sheets and nickel nanoparticles with low density (55−192 mg/cm 3 ), high electric conductivity (0.8 × 10 3 to 4.5 × 10 4 S/m), and high specific surface area (49− 105 m 2 /g). The graphene/Ni aerogel fibers (GNAFs) were synthesized initially from reduced graphene oxide hydrogel fibers followed by an electroless plating process. Further investigations have demonstrated that the resulting GNAFs possess excellent electrothermal property, faster electrothermal response, high mechanical and electrical stability as the electric wire, and excellent EMI shielding performance as the composite filler. The saturated temperature of GNAFs can reach 174 °C with an applied voltage of only 5 V, and the heating rate surpasses those of commercial Kanthal and Nichrome wires about 2.1 times and 2.6 times, respectively. The EMI shielding effectiveness of GNAFs is higher than 30 dB at the long bandwidth of 12.5−20 GHz. Specifically, it can shield more than 99.99% of the incident wave at the bandwidth of 15−20 GHz.

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GO/Fe3O4/PEI nanocomposites were prepared by chemical strategy, they show enhanced adsorption performance for Cu2+ due to the extraordinary complex ability of PEI. Moreover, they can be easily separated due to the superparamagnetism of Fe3O4.