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In this work, 1-aminoethyl-3-methylimidazolium bromide ionic liquid was used to modify the surface of graphene nanosheets (GNs) through "π–π" interaction to achieve good dispersion and conductivity. By introducing ionic liquid-modified graphene nanosheets (IGNs) into the PI matrix, the ultra-lightweight and multifunctional IGNs/PI aerogels were prepared via freeze-drying and thermal imidization. Benefiting from the porous structure and the introduction of conductive IGNs, the IGNs/PI aerogels exhibit excellent electromagnetic wave (EMW) absorption properties, compression properties, thermal insulation properties and thermal stability. Notably, when the volume content of IGNs is 10%, the IGNs/PI-10 aerogels show the best EMW absorption performance with a minimum reflection loss (RLmin) of −24.8 dB at 2.44 mm and an effective absorption bandwidth (EAB) of 3.6 GHz at 3.00 mm. These promising characteristics including excellent EMW absorption, compression properties and thermal insulation endow IGNs/PI aerogels great application prospects as multifunctional EMW absorbers. [ABSTRACT FROM AUTHOR]

Wool-spherical carbon nanotube microspheres/Nb 2 O 5 (CNTMs/Nb 2 O 5) for use as novel electromagnetic wave (EMW)-absorbing materials were successfully prepared by a simple hydrothermal method. The unique structure of the prepared composites was found to have a significant influence on the EMW absorption performance. Wool-spherical CNTMs/Nb 2 O 5 with a 5-wt% ultralow filling load shows significantly improved EMW absorption performance compared to the common carbon nanotubes/Nb 2 O 5 (CNTs/Nb 2 O 5) with two-dimensional linear structure. A minimum reflection loss (RL min) of − 65 dB is obtained for the CNTMs/Nb 2 O 5 with a thickness of 3.96 mm, and the widest effective absorption bandwidth (EAB) of 8.32 GHz is achieved at a thickness of 3.65 mm. The wool-spherical CNTMs/Nb 2 O 5 could serve as a reference for developing novel application strategies for materials with enhanced EMW absorption. • The CNTMs/Nb 2 O 5 with wool-spherical structure is facilely prepared. • The RL min of − 65 dB and the widest EAB of 8.32 GHz are achieved. • The synergistic effects of multiple loss mechanisms improve microwave absorption. [ABSTRACT FROM AUTHOR]

Chain-spherical V 2 O 5 /C composites were prepared by using dandelion fibers as bio-templates through a simple vacuum-assisted immersion method, and their microstructure and electromagnetic wave (EMW) absorption properties were investigated. Results indicated that the EMW absorption performance of dandelion fibers is effectively improved by introducing V 2 O 5 and constructing chain-spherical structure. Notably, the minimum reflection loss (RL min) of V 2 O 5 /C composites with a thickness of 2.35 mm is reached −34.05 dB at 17.52 GHz, and the maximum effective absorption bandwidth (EAB) of the composites is up to 7.52 GHz at 2.85 mm. The improvement in EMW absorption performance is mainly ascribed to the synergistic effects of the increased multiple reflections and scattering, enhanced polarization loss and conduction loss, and impedance matching characteristics. The chain-spherical V 2 O 5 /C composites exhibit great potential as promising candidates for high-performance EMW absorbers. • The V 2 O 5 /C composites with a chain-spherical structure are facilely prepared. • The synergy effect of multiple loss mechanisms enhances microwave absorption. • The RL min of −34.05 dB and the widest EAB of 7.52 GHz are achieved. [ABSTRACT FROM AUTHOR]

With the widespread application of electronic devices, multifunctional electromagnetic wave (EMW) absorbing materials suitable for complex high-temperature and high-pressure environments, have attracted tremendous research attention. Herein, multifunctional polyimide (PI) composites doped with fluffy Nb 2 O 5 /CNTs microspheres (NBCP) were prepared by combining the ultrasonic spraying process and freeze-drying technique. Introduction of fillers results in the formation of diverse conduction paths and heterogeneous interfaces, which enhance the dielectric loss. Furthermore, the multi-porous structure of the PI matrix induces multiple reflection scattering events and improves the impedance matching. Such a multi-loss mechanism endows NBCP with an excellent EMW absorption performance. At 15 vol% filling, the minimum reflection loss is −41.66 dB, the effective absorption bandwidth is 2.63 GHz, and the radar cross-section is reduced by 85%. Furthermore, NBCP exhibits outstanding mechanical properties and a thermal insulation of over 100 °C in thermal environment at 150 °C. The proposed multifunctional NBCP is thus an efficient EMW absorber that offers significant potential for applications in harsh environments. [Display omitted] • Lightweight Nb 2 O 5 /CNTs/PI (NBCP) polymer-based materials were fabricated by spray and freeze-drying techniques. • NBCP-15 exhibits minimal reflection loss of −41.66 dB, an effective absorption bandwidth of 2.63 GHz, and radar cross section reduction of 85%. • NBCP has integrative properties of microwave absorption, thermal management, and compression resistance. [ABSTRACT FROM AUTHOR]

Novel NiSe 2 -based composites loaded with carbon nanotubes (CNTs) and graphene (GNs), respectively, were successfully synthesized via a facile hydrothermal reaction, aiming to enhance the electromagnetic wave (EMW) absorption performance. Microstructure, morphology, dielectric properties and EMW absorption performance of as-prepared NiSe 2 /CNTs and NiSe 2 /GNs composites were explored. Results showed that both NiSe 2 /CNTs and NiSe 2 /GNs composites exhibited improvement in EMW absorption compared to pure NiSe 2 , especially NiSe 2 /GNs showed the best EMW absorption performance. NiSe 2 /GNs composites demonstrated an exceptional minimum reflection loss (RL min) of −52.10 dB at a thin thickness of merely 1.71 mm, accompanied by a wide effective absorption bandwidth (EAB) of 4.1 GHz. However, the EMW absorbing performance of NiSe 2 /CNTs composites was slightly lower than that of NiSe 2 /GNs composites, showing an RL min of −45.10 dB and an EAB of 3.76 GHz at a thin thickness of 1.60 mm. Such significantly enhanced absorption capability of NiSe 2 /GNs composites can be attributed to the synergistic interplay of desirable impedance matching and efficient attenuation ability. These findings highlight the potential of NiSe 2 -based composites loading with carbon conductive fillers as highly promising contenders for high-performance EMW absorption materials. [Display omitted] • Nickel selenide-carbon composites with high electromagnetic wave absorption performance were prepared. • NiSe 2 /GNs had a minimum reflection loss of −52.10 dB and an effective absorption bandwidth of 4.1 GHz at 1.71 mm. • The enhanced electromagnetic wave absorption mechanism was investigated in detail. • The Radar cross section of NiSe 2 /GNs and NiSe 2 /CNTs composites was assessed to deeply investigate absorption mechanism. [ABSTRACT FROM AUTHOR]

The pompon-shaped Nb 2 O 5 /carbon nanotubes composite microspheres (NCM) were successfully synthesized via a spraying technique as electromagnetic wave (EMW) absorption materials. The comprehensive investigation process involved the microstructure, phase composition, EMW absorption property, and corresponding mechanisms of the as-fabricated NCM. The combination of CNTs and Nb 2 O 5 not only provides multiple attenuation mechanisms but also promotes impedance matching. Furthermore, substantial newly-formed heterogeneous interfaces in NCM enhance the relaxation polarization process. Additionally, the distinctive pompon-shaped morphology of NCM enhances multiple reflection and scattering of the EMW, thereby facilitating the extension of transmission paths for charge. NCM-3 demonstrated significantly superior EMW absorption performance, with an effective absorption bandwidth (EAB) of 5.28 GHz and a minimum reflection loss (RL min) of −30.52 dB at a mere thickness of 1.97 mm. This work could provide critical guidance for the exploration of new binary materials for EMW absorption. [Display omitted] [ABSTRACT FROM AUTHOR]