Constructing crystalline/amorphous heterojunction in FeCo@C nanoboxes for enhanced electromagnetic wave absorption

The advanced electromagnetic applications urgently require high performance absorbers with sophisticated structural and compositional design. An effective strategy is to construct a three-dimensional hollow structure, with enhanced electromagnetic wave dissipation capacity over a wide effective absorption bandwidth. However, a major challenge remains due to a single loss mechanism system derived from the conventional hollow nanobox structure, which seriously causes impedance mismatch and lack of polarization centers. Herein, we innovatively construct novel hollow structure FeCo@C (CMFC) with crystalline/amorphous heterojunction FeCo/C particles by cation exchange method, thereby achieving enhanced electromagnetic wave absorption. The CMFC achieves Ku-band effective absorption with a reflection loss of −50.57 dB and effective absorption bandwidth of 5.35 GHz at 1.8 mm. The CMFC exhibits excellent microwave absorption performance due to the presence of crystalline/amorphous FeCo/C heterojunction, which is attributed to the balanced dielectric loss and optimized impedance matching characteristics. CST simulations demonstrate that the CMFC has a radar scattering interface reduction value as high as 26.12 dBm (Wu et al., 2023) [2] at a scattering angle of 0°. This work provides new ideas for the rational design of hollow nanostructures with heterojunction particles for efficient microwave absorption. A heterojunction-configurated absorber with hollow structure is developed via amorphous carbon and prussian blue analogs derivatives. The unbroken hollow structure not only played an important role in the formation of the hybridized carbon skeleton, the accumulation of graphitic carbon layers and the growth of cobalt and iron metal particles, but also endowed the composites with matched impedance and excellent attenuation capability. Classic hollow structured prussian blue analogs derivatives (CMFC) greatly enhance the microwave absorption. [Display omitted] •Heterojunction-configurated absorbers can resolve the impedance mismatch problem.•The connected carbon-skeletons increase the path of electromagnetic wave attenuation.•Hollow nanoboxes precisely synthesized by cation-exchange strategy.•Synergistic effects of dielectric and magnetic losses based on nanoboxes enhance the microwave absorption performance.