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Developing high-performance microwave absorption (MA) materials becomes an urgent concern in the field of electromagnetic protection. Constructing porous framework is an efficient approach to MA owing to the abilities of adjusting impedance matching and providing more reflection and scattering paths for electromagnetic waves. Herein, a cellulose nanofibril (CNF)/honeycomb-like carbon-shell encapsulated FeCoNi@C/carbon nanotube (CNT) composite aerogel was fabricated via a facile freeze-drying method. The super-lightweight composites showed a distinctive gradient structure for reflection and scattering inside aerogel pores, micrometer small pores, and nano-fillers on the pore walls. The composite aerogel showed an ideal minimum reflection loss (RL min) of −43.6 dB and remarkable adjustable effective absorption bandwidth (EAB) of 12.18 GHz due to good impedance matching, unique gradient porous structure, and synergies of multiple loss mechanisms. Therefore, this work will provide a viable strategy to improve the MA capability of absorbers by taking full advantage of constructing gradient reflection and scattering porous structure. [Display omitted] [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) heterogeneous flower-like spherical MoS 2 /CNTs composites with worm-like interfaces were successfully fabricated by a simplified solvothermal reaction to achieve superb electromagnetic wave absorption (EWA) properties. The microstructure characteristics, morphology features, EWA performance and associated mechanism of as-prepared specimen were systematically analyzed. The incorporation of MoS 2 resulted in the establishment of a 3D conductive network and a substantial augmentation of the heterogeneous interfaces between MoS 2 and carbon nanotubes (CNTs), thereby inducing an amplified conductance loss and polarization loss, respectively. Moreover, the fabrication of 3D architecture not only enhances the structural robustness of the composites, but also broadens the avenue for electromagnetic wave (EW) reflection and scattering, thus augmenting the absorption of EW energy. As a result of the synergistic effect of augmented attenuation capability as well as optimized impedance matching, the EWA performance of materials was outstanding, with a minimum reflection loss (RL min) of −52.1 dB and an effective absorption bandwidth (EAB) of 1.93 GHz achieved at a thin thickness of 2.46 mm in the X band. This research will serve as a meaningful point of reference for exploring 3D flower-like spherical structure of EW absorber. [Display omitted] • 3D heterogeneous flower-like spherical MoS 2 /CNTs composites were prepared. • MoS 2 /CNTs composites have worm-like interfaces. • Superior EMA performance was achieved with minimum reflection loss was −52.1 dB. • The impedance matching and polarization loss was enhanced with MoS 2. • The electromagnetic wave absorption mechanism was proposed. [ABSTRACT FROM AUTHOR]

With the increasingly serious electromagnetic pollution, the urgent demands for electromagnetic wave absorption (EMWA) materials are gradually developing towards performance integration and multi-dimensional scales. Herein, the enoki-like carbon nanotubes (CNTs) coated with nickel particles (CNT@Ni) were synthesized by a catalytic thermal decomposition method. The resulting CNT@Ni composites exhibited excellent EMWA performances with a minimum reflection loss value of − 60.4 dB at a thickness of 2.97 mm. It benefited from the synergy of collaborative electrical and magnetic losses and hierarchical structure. The conductive pathways formed by the intertwined CNTs greatly improved the EMWA capacity of the material, enabling large amounts of electromagnetic waves to enter the material for conversion and dissipation. In addition, the inherent graphite defects and oxygen-containing groups formed on the material surface during the process of high-temperature treatment provided polarization centers for dipole polarizations. More importantly, the abundant heterogeneous interfaces enhanced the interface loss effects of the material. This simple preparation strategy of the CNT-based EMWA material will provide a design inspiration for the novel electromagnetic absorber. [Display omitted] • A simple preparation method of CNTs coated with nickel particles was proposed. • Enoki-like structures provided rich heterogeneous interfaces. • A superior RL min value of − 60.4 dB was obtained based on complex loss mechanisms. [ABSTRACT FROM AUTHOR]