Facile synthesis of CoxFey@C nanocomposite fibers derived from pyrolysis of cobalt/iron chelate nanowires for strong broadband electromagnetic wave absorption

Nowadays, constructing electromagnetic wave (EMW) absorbing materials with high absorption strength and wide response frequency is an urgent demand and also a challenge. In this work, the bimetallic organic precursors of cobalt/iron nitrilotriacetic acid chelate nanowires (Co/Fe-NTAC) were prepared by one-step hydrothermal self-polymerization strategy. Then, the CoxFey@C nanocomposite fibers with different Co/Fe atomic ratios were synthesized by directly calcining the Co/Fe-NTAC precursors. Notably, when the atomic ratio of Co/Fe is 1:1, the sample exhibits high-efficient microwave absorption performance with the minimum reflection loss (RL) of −117.8 dB, whose effective absorption bandwidth (EAB, RL ≤ −10 dB) reaches up to 12.6 GHz (5.4–18 GHz) at the same thickness. The outstanding EMW attenuation properties are attributed to the strong magnetic loss, multiple heterogeneous interface polarizations, synergistic effects between magnetic cores and dielectric shells, as well as optimal impedance matching. Especially, the heterointerfaces polarization behavior and ferromagnetic coupling effect were verified by High-Frequency Structure Simulator (HFSS). The Radar Cross-Sectional (RCS) values of the optimized sample are all lower than −10 dBm2 in the range of −60° < θ < 60°, which can achieve almost full-angle coverage in the practical environment. This work provides inspiration and strategy for the facile construction of high-intensity and ultra-wideband EMW absorbers.