Integrated micro and nanostructures, heterogeneous components, defects, and interfaces is the way to develop high-performance microwave absorbing materials. However, there still needs to be more precise experimental routes and effective validation. In this work, by a continuous process of vacuum sintering, hydrothermal, and carbon thermal reduction, magnetic FeCo nanoparticles were successfully embedded on the hollow double-shell mesoporous SiC@C surface, thus solving the challenges of a single component loss mechanism. The hollow double-shell nanostructure introduces air to enhance impedance matching while significantly reducing the density of the material. The extensive defects and heterogeneous grain boundaries effectively enhance the polarization loss capacity. The magnetic loss mechanism introduced by the magnetic particles effectively improves the impedance matching properties of the material. The synergy of these multiple advantages has enabled the SCFC2-8 (here SiC@C@FeCo is abbreviated to SCFC, 2 represents the initial metal ion content, and 8 represents the hydrothermal time) sample to achieve an adequate absorption bandwidth of 6.09 GHz at 2.0 mm. With a minimum reflection loss of −60.56 dB, the absorption bandwidth can cover the entire C, X, and Ku bands by adjusting the matching thickness (1.3–4.0 mm). This work provides a valuable paradigm for the deeper exploitation of microwave absorption potential and guides the development of other high-performance materials.

Achieving synergistic absorption of electromagnetic waves (EMWs) in the mid-high frequency and absorption band conversion is an urgent problem. However, the present solution is usually a straightforward mixture of magnetic component-carbon component. Hereby, we optimize the magnetic properties and electrical relaxation response from a chemical synthesis perspective. Through integrated design, the contents of carbon components and multi-dimensional morphology are controlled by retaining strong magnetic properties. The morphology design and the construction of heterogeneous interfaces will boost the intense response of charge in the surrounding to enhance the polarization effect. The multi-dimensional structure and electromagnetic (EM) properties of the sample after optimized engineering have an extremely powerful absorption conversion effect on EMW energy. NiCo@C particles ultimately achieve synergistic absorption effects at low thickness (d < 3.5 mm) at middle frequencies (6–10 GHz) and high frequencies (10.5–18 GHz). Our work establishes a correlation mechanism between the physical and chemical properties of materials and EM parameters. It also provides insight into the synergistic absorption of EMWs in the mid-high frequency and absorption band conversion strategies.

The development of multifunctional materials and synergistic applications of various functions are important conditions for integrated and miniaturized equipment. Here, we developed asymmetric MXene/aramid nanofibers/polyimides (AMAP) aerogels with different modules using an integrated molding process. Cleverly asymmetric modules (layered MXene/aramid nanofibers section and porous MXene/aramid nanofibers/polyimides section) interactions are beneficial for enhanced performances, resulting in low reflection electromagnetic interference (EMI) shielding (specific shielding effectiveness of 2483 (dB·cm³)/g and a low R-value of 0.0138), high-efficiency infrared radiation (IR) stealth (ultra-low thermal conductivity of 0.045 W/(m·K) and IR emissivity of 0.32 at 3–5 μm and 0.28 at 8–14 μm), and excellent thermal management performances of insulated Joule heating. Furthermore, these multifunctional AMAP aerogels are suitable for various application scenarios such as personal and building protection against electromagnetic pollution and cold, as well as military equipment protection against infrared detection and EMI.