Large-Scale Nanofiber Manufacturing| Component-based modulation engineering to improve magnetoelectriccoupling for self-anticorrosion broadband absorption

Associate Professor Lan Di from Hubei University of Automotive Technology: Component Modulation to Improve Magnetoelectric Coupling for Anti-corrosion and Broadband Absorption

The continuous advancement of fifth-generation (5G) wireless communication technology has ushered the world into an intelligent era. However, the widespread use of electronic communication technologies inevitably generates electromagnetic radiation. Therefore, exploring electromagnetic wave absorbers capable of effectively dissipating electromagnetic waves into heat is considered a viable solution. Nevertheless, developing electromagnetic wave (EW) absorbing materials with self-protective properties and high absorption capabilities remains a challenging task given the variability of electromagnetic pollution.

Recently, Associate Professor Lan Di from Hubei University of Automotive Technology and Professor Wu Guanglei's team at Qingdao University published their latest research, "Component-based modulation engineering to improve magnetoelectric coupling for self-anticorrosion broadband absorption," in the journal Carbon. The researchers embedded cubic NiCoFe-PBA into fibers via electrospinning and utilized the reducing properties of carbon at high temperatures to prepare NiCoFe@CNFs composites. Due to the inherent high conductivity of carbon fibers and structural design, the densely interwoven conductive network significantly enhances electron transport, thereby improving the material's dielectric loss properties. Additionally, optimized impedance matching through interfacial polarization induced by component control endowed the composite with excellent self-anticorrosion and electromagnetic wave absorption performance.At a matching thickness of 2.3 mm, NiCoFe@CNFs achieved a minimum reflection loss (RL_min) of −74.6 dB, with a maximum effective absorption bandwidth (EAB_max) of 7.68 GHz at a thickness of 2.7 mm. Furthermore, radar cross-section (RCS) calculations demonstrated the significant potential of NiCoFe@CNFs for practical applications in military stealth protection technologies.

Fig. 1: Preparation process and morphology of NiCoFe@CNFs composites.

As shown in Figure 1, various PBAs from binary to ternary were synthesized via a simple solution co-precipitation method. First, citrate ions coordinated with metal ions. Then, the metal-citrate complexes reacted with hydroxyl groups to form nuclei. Finally, crystal growth yielded NiCoFe-PBA precursors. Subsequently, PAN and NiCoFe-PBA were dissolved in DMF to prepare the spinning solution. Gray fibrous mats were obtained via electrospinning, pre-oxidized at low temperatures, and then calcined at high temperatures to produce NiCoFe@CNFs composites.

The synthesized NiCoFe-PBA exhibited relatively uniform distribution, with cubic block structures ranging from 40–70 nm in diameter. Carbonized fibers formed an abundant interwoven conductive carbon network, with fiber diameters ranging from 80 to 120 nm. NiFe and CoFe alloys were successfully encapsulated within the carbon fibers, retaining their original cubic structures, with lattice fringe spacings of 0.207 nm and 0.201 nm, respectively. The well-dispersed NiCoFe alloys inside the fibers enhanced conductivity and promoted conduction loss.The heterogeneous interfaces between carbon fibers and magnetic particles induced interfacial polarization, while the strong magnetic loss from magnetic alloys (MEAs) enhanced magnetic coupling. These mechanisms synergistically improved attenuation capabilities.

Fig. 2: Electrochemical characterization of composites in NaCl solution.

As shown in Figure 2, NiCoFe@CNFs exhibited the lowest self-corrosion tendency. Higher corrosion potential and lower corrosion current indicated superior anticorrosion performance. Tafel curves revealed that NiCoFe@CNFs had the highest corrosion potential and lowest corrosion current, demonstrating strong self-anticorrosion capability. This property originated from the protective effect of carbon fibers. The interwoven carbon network provided a large specific surface area, while graphitized carbon shells acted as barriers, creating a "maze effect" that delayed corrosion pathways.

Fig. 3: Electromagnetic wave absorption performance of NiCoFe@CNFs, NiFe@CNFs, and CoFe@CNFs.

Experimental results confirmed that electrospun samples outperformed non-electrospun ones. Among all samples, NiCoFe@CNFs showed the best performance due to its conductive network facilitating electron transition and migration, thereby increasing conduction loss. The introduction of magnetic particles further enhanced magnetic loss, achieving a synergistic effect between dielectric and magnetic losses.

Fig. 4: (a–f) Electromagnetic parameters; (g–i) dielectric and magnetic loss curves of NiCoFe@CNFs, NiFe@CNFs, and CoFe@CNFs.

Fig. 5: (a–f) Cole-Cole curves of various composites; (g) attenuation constant; (h) impedance matching; (i) C₀ values.

Fig. 6: Absorption mechanism of NiCoFe@CNFs.

In summary, this work encapsulated NiCoFe alloys inside carbon fibers via solution co-precipitation, electrospinning, and thermal reduction. The composite leveraged multiple loss mechanisms (polarization and magnetic losses) to attenuate electromagnetic waves effectively. The interwoven carbon fibers promoted multiple reflections and scattering of electromagnetic waves, while NiCoFe MEAs enhanced magnetic loss. Additionally, dense graphitized carbon prevented oxidation of medium-entropy alloys and endowed the composite with exceptional self-anticorrosion properties.

This study expands the application of 1D materials in electromagnetic wave absorption and self-anticorrosion, providing guidance for designing high-performance composites.

Paper Link: https://www.sciencedirect.com/science/article/abs/pii/S0008622325003410