Developing a Superhydrophobic Absorption-Dominated Electromagnetic Shielding Material by Building Clustered Fe₃O₄ Nanoparticles on the Copper-Coated Cellulose Paper

Corrosion-resistant electromagnetic shielding materials with high conductivity and excellent magnetic properties are urgently needed to resolve the issue of electromagnetic radiation pollution. Herein, the renewable and easily degradable cellulose paper after tannin-assisted silver-nanoparticle deposition was designed as the substrate. An electroless copper-plated paper (ECP) with a high conductivity of 4167 s/cm and a low sheet resistance of 5.17 mΩ/sq was used as a conductive layer. The superhydrophobic magnetic surface with a contact angle of 153.5° and a sliding angle of 3.2° was prepared by spraying a mixture of polydimethylsiloxane and clustered Fe 3 O 4 microspheres synthesized by a one-step hydrothermal method. Fe 3 O 4 microspheres were used to construct the surface micro–nano hierarchical structure and improve the impedance matching, and polydimethylsiloxane was used to provide a low surface energy and facilitate the adhesion of ECP to clustered Fe 3 O 4 microspheres. The synergistic effect of the conductive and magnetic layers resulted in the cellulose paper, showing absorption-dominated electromagnetic shielding characteristics with electromagnetic interference shielding effectiveness >50 dB (absorption: reflection ∼95:5). The study provides a promising method for preparing wave-absorbing-based shielding materials with a wide application.