Utilizing ion-etching strategy to construct ultra-lightweight CoNi alloy-modified electrospun carbon fiber composites for efficient electromagnetic wave absorption

In the practical application of electromagnetic wave (EMW) absorbers, two important factors that simultaneously meet the lightweight characteristics and efficient absorption performance still face considerable challenges. In this work, the ultra-lightweight CoNi alloy nanoparticles uniformly distributed modified carbon nanofiber composites (CoNi@CNFs) was prepared by an ion-etching strategy. The carbon fibers create a three-dimensional conductive network that enhances the absorber’s conduction loss capability. The polarization loss is enhanced by the defects in the carbon skeleton and the numerous heterogeneous interfaces formed between the carbon fibers and the surface of CoNi metal particles. The impedance matching property of CoNi@CNFs is optimized by the magnetic dielectric synergistic effect produced by the Ni²⁺ etching process. At a frequency of 17.58 GHz, the minimum reflection loss (RL_min) can reach − 52.34 dB, and the effective absorption bandwidth covers the complete Ku band at 7.0 GHz (11.0–18.0 GHz). In the range of − 60° to 60°, the radar cross-section values of the samples, calculated using CST simulation, are less than − 10 dBm². This is critical for realizing the stealth capability of EMWs in high-frequency environments. This study provides an effective strategy for developing highly absorbent, lightweight EMW absorbers with practical potential applications.