From 3D Forest to 2D Protection: Magnetic Wood with Reconfigurable Conductive Pathway for Versatile Electromagnetic Interference Shielding

Abstract Wood‐derived carbon has great potential in building sustainable, lightweight electromagnetic interference (EMI) shielding materials. However, developing a straightforward method for fabricating materials that exhibit both high EMI shielding effectiveness (SE) and multifunctionality remains a challenge. Herein, the carbonized wood/epoxy/iron composite (C/EP/Fe) with hierarchical porous architecture is synthesized by encapsulating magnetic nanoparticles inside the conduits of wood‐derived carbon materials through via a simple two‐step process. Hot pressing is used to convert the conductive pathways, the inherent 3D honeycomb structure into a 2D grid. This structural transition, synergized with the magnetic nanoparticles, markedly enhanced the EMI SE. At a density of 392.26 mg cm −3 and a thickness of 1.05 mm, the C/EP/Fe‐4 achieved an EMI SE of 95.3 dB in the X‐band and allowed for tunable EMI shielding performance through adjustments in rotation angles. Furthermore, the material demonstrated shielding efficiency exceeding 99.999999% across the C‐K bands, with excellent EMI SE values consistently above 89 dB. In addition to its superior EMI shielding performance, the C/EP/Fe exhibited a suite of multifunctional properties, including rapid Joule heating, excellent thermal stability, flame retardancy, hydrophobicity, and reliable mechanical strength.