NiCo-C/CNF Aerogel-Based Composites for Absorption-Dominant Electromagnetic Interference Shielding

Metal–organic-framework-derived magnetic carbon particles have attracted attention as promising absorbers for electromagnetic interference (EMI) shielding because they combine porous architectures, conductive carbon networks, and magnetic loss capability. In this work, NiCo-C magnetic particles were integrated with cellulose nanofiber (CNF) to construct anisotropic NiCo-C/CNF aerogels through unidirectional freeze-casting, freeze-drying, and thermal treatment, followed by polymer infiltration to form lightweight EMI shielding composites. The aligned porous CNF framework provides pathways for electromagnetic wave propagation and internal reflections, while NiCo-C particles contribute magnetic loss, interfacial polarization, and conductive attenuation. Structural and chemical analyses confirmed the evolution from precursor particles to porous NiCo-C, including the formation of defective graphitic carbon, compositional redistribution of Co, Ni, C, O, and N, and surface electronic reconstruction after Ni incorporation and carbonization. SEM and TEM observations revealed the morphological transition from well-defined particles to a heterogeneous porous magnetic carbon structure, beneficial for wave dissipation within the aerogel network. In addition, a reflective layer was introduced on one side of the composite to promote repeated attenuation of incident electromagnetic waves inside the porous structure, enhancing absorption-dominant shielding behavior. Unlike reflection-dominant shields, which may cause secondary electromagnetic pollution, absorption-dominant EMI shielding materials are increasingly important for future electronic devices, wireless systems, electric vehicles, and high-density energy storage modules. The NiCo-C/CNF aerogel-based composite suggests a viable strategy for designing lightweight, anisotropic, and absorption-oriented EMI shielding materials by coupling magnetic loss components with directional porous architectures.