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[Display omitted] • The fabricated UIO-la-CoN-rGO aerogel possesses the properties of hydrophobic, anti-corrosion, heat insulation, infrared stealth and electromagnetic wave absorption. • The UIO-la-CoN-rGO aerogel achieves high EMW absorbing performance, with reflection loss of −44.8 dB and effective absorbing bandwidth (EAB) of 7.28 GHz. • The UIO-la-CoN-rGO aerogel shows an impedance value of 1.5 × 105 Ω·cm2 after being soaked in 3.5 % aqueous NaCl for 30 d with an anti-corrosion efficiency of 99.149 %. • The introduction of heteroatoms enriches the defect sites of the materials, thus increasing the interfacial polarization and dipole polarization. In addition to having a superior electromagnetic wave (EMW) absorption profile, materials of this type that are applied in complex and extreme environments must be hydrophobic, anti-corrosive, heat insulating and infrared stealth. In the described investigation, a multifunctional UIO-la-CoN-rGO aerogel that possesses all of these properties was fabricated by using a hydrothermal and freeze drying process. Lauric acid (la) is incorporated into this aerogel to enlarge pore sizes and enhance hydrophobicity of the Zr-based metal organic framework (UIO-66) component. The large interfacial and dipole polarization caused by anchoring UIO-66 nanospheres to the Co,N co-doped graphene nanosheets results in a high EMW absorbing performance, reflected in a minimum reflection loss (RL min) of −44.8 dB and a wide effective absorbing bandwidth (EAB) of 7.28 GHz. In addition, the aerogel displays high levels of hydrophobicity, anti-corrosiveness, heat insulation and infrared stealth. For example, UIO-la-CoN-rGO has a water contact angle of 142.5°and a surface temperature that remains nearly unchanged after more than 1 h at 100 ℃. Moreover, the UIO-la-CoN-rGO coating gives the aerogel an impedance value of 1.5 × 105 Ω·cm2 after being soaked in 3.5 % aqueous NaCl for 30 d, and an anti-corrosion efficiency of 99.149 %. The results of this study provide guidance for the design of multifunctional EMW absorbing materials that function in complex environments. [ABSTRACT FROM AUTHOR]

Electromagnetic waves constitute an essential element of societal progress, and the environmental impact resulting from using electromagnetic waves warrants significant considerations. Carbon materials have garnered considerable attention in the functional domain owing to their remarkable electrical conductivity and dielectric characteristics. Notably, spherical carbon materials, characterized by their substantial specific surface area and tunable dielectric properties, have emerged as efficient additives for microwave absorbers. These materials excel in absorbing electromagnetic energy while minimizing energy dissipation. When incorporated into absorbers of varying compositions, sizes, and morphologies, these carbon spheres facilitate the synergistic operation of multiple loss mechanisms, containing conductive loss, magnetic loss, and polarization loss. This concerted action significantly enhances the electromagnetic wave absorption performance. This paper offers a comprehensive review of the advancements in carbon sphere-based materials designed for absorbing electromagnetic waves. It also furnishes an intricate exposition of the methodologies employed in their preparation and a meticulous analysis of their performance. The paper summarizes the microstructural attributes and mechanisms governing electromagnetic wave absorption in various carbon sphere configurations, considering factors such as composition, morphology, size, and structure. In conclusion, this study forecasts the potentials of carbon sphere-based nanomaterials in the realm of electromagnetic waves, along with an assessment of forthcoming research focal points and conceivable challenges. The classification and the preparation of carbon spheres and their composites in recent years are reviewed, and the corresponding electromagnetic wave absorption properties and mechanisms are discussed in detail. [Display omitted] • This paper describes the classification and preparation of carbon spheres and their composites. • Previous work and research progress on carbon spheres and their composite as electromagnetic wave absorbing materials are summarized. • This paper discusses the advantages, challenges and prospects of carbon spheres and their composite as electromagnetic wave absorbing materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • The fabricated FeNi-MOF-rGO aerogels exhibits remarkable EMW absorption performances with strong RL and broad EAB at the thickness of 2.9 mm (−48.3 dB and 8.32 GHz) whereas the filling contents are just 5 %. • The morphology and structure of MOF are regulated by electron transfer of GO and the obtained MOF with unique strip or regular octahedral shape results in vast heterojunction interfaces. • The electron transfer was further confirmed by DFT differential density and Bader charge analysis and the interfacial polarization of the material was confirmed by finite element simulation. Graphene and its derivatives have become the star materials in the field of electromagnetic wave (EMW) absorption, and have been widely studied because of their unique structure and excellent properties. However, the high electrical conductivity of graphene-based material leads to poor impedance matching performances, so it often needs to be annealed at high temperatures, which is a intricate procedure and cause the waste of energy. Herein, we develop a convenient strategy to synthesize metal organic framework-reduced graphene oxide (MOF-rGO) aerogels through facile hydrothermal and freeze drying procedure. Firstly, the excessive electrons on graphene can be transferred to MOF, in this way, no annealing is needed. Secondly, the morphology and structure of MOF can be regulated electronically to endow the material with rich heterojunction interfaces and enhance its interfacial polarization. Thirdly, the synthesized aerogels satisfy the requirements of thin thickness, low density and light weight. The fabricated Ni-MOF-rGO and FeNi-MOF-rGO aerogels exhibit remarkable EMW absorption performances with strong reflection loss (RL) and broad effective absorption band (EAB) at the thickness of 2.4 (−47.8 dB and 7.84 GHz) and 2.9 mm (−48.3 dB and 8.32 GHz) whereas the filling contents are just 5 %. Moreover, the attenuation capacity of the fabricated aerogels are verified through the radar-section simulation and the interfacial polarization loss are confirmed by the COMSOL analogue simulation. In a word, this work provides a new afflatus and inspiration for the design of graphene-based EMW absorption materials. [ABSTRACT FROM AUTHOR]

The lightweight and efficient electromagnetic wave (EMW) absorption materials have been a popular research topic. In this work, MnO 2 @graphene (MnGr) nanofibers with core-shell structure were synthesized by a one-step hydrothermal method. This one-dimensional linear structure was further self-assembled into a three-dimensional hierarchical MnGr aerogel network structure due to the interlayer forces of graphene sheets. The addition of graphene greatly enhances the interfacial polarization. The significant differences in electronic structure and work function between the outer graphene layer and the inner MnO 2 layer greatly enhance the interfacial polarization. The formation of 3D hierarchical MnGr aerogel network structure constructs more fast electron transport channels. With the addition of graphene oxide at 7.5 wt% of the theoretical yield of MnO 2 , MnGr-7.5 exhibits excellent wave absorption properties. The effective absorption bandwidth (EAB) can reach 6.40 GHz at 2.2 mm. And the minimum reflection loss (RL min) is − 41.3 dB at 1.8 mm and 17.36 GHz. Finite element physical simulation is used to simulate the response of 3D conductive network to electromagnetic wave. Through calculation, it is found that the inter-lap network structure is beneficial to enhance the loss. The low-cost MnO 2 compounded with a small amount of graphene has excellent wave absorption performance and a great application prospect. • A three-dimensional hierarchical MnO 2 @graphene (MnGr) aerogel network structure is constructed. • The fabricated MnO 2 @graphene aerogel has the advantages of light weight, wide effective bandwidth and strong absorption. • Using COMSOL simulation to study the response of conductive networks to electromagnetic wave. [ABSTRACT FROM AUTHOR]