A facile strategy for customizing multifunctional magnetic‑dielectric carbon microflower superstructures deposited with carbon nanotubes

Abstract

The novel fabrication of multiple components and unique heterostructure can inject infinite vitality into the electromagnetic wave (EMW) attenuation field. Herein, through the self-assembly of polyimide complexes and catalytic chemical vapor deposition, porous carbon microflowers were synthesized accompanied by carbon nanotubes (CNTs). By regulating the metal ions, the composition and structure of the as-obtained hybrids are modified correspondingly, and thus the adjustable thermal management and EMW absorption capabilities are obtained. In detail, the rich pores and huge specific surface area endow the hierarchical structures with distinguished thermal insulation ability (λ<0.07). The carbon framework and CNTs are beneficial for consuming EMWs via conductive loss and defect polarization loss while reducing the filling ratio and thickness. The doped heteroatoms and abundant heterointerfaces generate ample dipole polarization and interface polarization losses (supported by DFT calculation). The metal nanoparticles uniformly embedded in the carbon framework offer optimized impedance matching, proper defect polarization, and suitable magnetic loss. Accordingly, the synergy of magnetic-dielectric balance and flower-like superstructure enables FNCFN2 and NNCFN2 to accomplish remarkable microwave absorbing capacity with thin thickness (14 wt.%). Therefore, respectable specific reflection loss and specific effective absorption bandwidth are acquired (215.39 dB mm^–1 and 22.10 GHz mm^–1, 257.23 dB mm^–1 and 22.12 GHz mm^–1 respectively), superior to those of certain renowned carbon-based absorbers. The simulation results of electric field intensity distributions, power loss density, and radar cross section reduction (maximum value of 36.02 dBm²) also verify the prominent radar stealth capability. Moreover, the customizable approach can be applied to other metals to obtain fulfilling behaviors. Henceforth, this work provides profound insights into the relationship between structure and performance, and proposes an efficient path for mass-producing multifunctional and high-performance EMW absorbers with excellent thermal properties.