Carbon nanofibers with small-sized Co nanoparticles and structural defects via a confined-coordination growth strategy toward electromagnetic wave absorption

Carbon nanofibers have emerged as promising candidates in realizing light-weight and high‑performance electromagnetic (EM) wave absorbing materials owing to their obvious merits such as long-range conductive networks, tunable dielectric properties and atomic-scale composition regulation. The existing challenges are how to optimize the surface impedance matching through structural design and realize multi-frequency response characteristics by the EM synergistic effects. Herein, we propose a confined-coordination growth strategy to anchor small-sized Co nanoparticles and simultaneously introduce structural defects on carbon nanofibers surface to realize light-weight and superior EM wave absorption. Interestingly, these post-coordinated MOFs derived small-sized Co nanoparticles can balance surface impedance, strengthen interfacial polarization and promote interfacial electric field polarization, and the sublimation of Zn species introduces structural defects to regulate the dielectric constant and trigger defect polarization. Benefiting from the cooperative advantages of matched impedance, long-range conductive networks, abundant dielectric-magnetic hetero-interfaces and structural defects, the minimum reflection loss of the carbon nanofibers reaches as high as -51.0 dB and the effective absorption bandwidth covers the whole Ku band with a broad bandwidth of 7.33 GHz. This strategy provides an integrated insight into optimizing the impedance characteristics of carbon nanofibers and manipulating the EM wave absorbing performance.