Synergistic Integration of Spherical Fe3O4 Nanoparticles and Wood-Sourced Carbon Surface for Highly Efficient Microwave Absorption via Interfacial Optimization

With the pervasive deployment of 5G communication systems and electronic devices, electromagnetic (EM) pollution has emerged as a critical environmental concern. Due to their wide availability, low cost, and ease of acquisition, biomass materials have been widely used in the preparation of electromagnetic wave absorption materials. Compared with traditional in situ impregnation methods, this study first employs chemical reagents to reduce the lignin content within balsa wood, thereby opening more pores and enhancing the loading capacity of iron salts. Subsequently, magnetic Fe3O4 particles are synthesized in situ, enabling the fabrication of magnetic wood-based composites. Compared with the non-impregnated pure carbonized samples, the reflection loss value of the samples with magnetic particles increased to −42.37 dB, corresponding to a matching thickness of 1.5 mm. This is much better than the −8.79 dB of the pure carbonized samples, and is attributed to multiple loss mechanisms. In addition, modern physical and chemical analysis instruments such as SEM, TEM, XRD, XPS, and Raman were used to characterize the physical and chemical changes of the materials. Finally, its applications in aerospace and thermal response were identified.