Sustainable electromagnetic shielding materials: The emerging potential of cellulose nanofiber-based composites - A...

The growing demand for lightweight, flexible, and environmentally sustainable materials for electromagnetic interference (EMI) shielding has intensified the interest in cellulose nanofiber (CNF)-based composites. Unlike conventional metal-based shielding materials, CNFs provide a biodegradable and mechanically robust platform capable of structural tailoring and strong interfacial interactions when combined with conductive fillers, such as MXene, AgNWs, PEDOT:PSS, and MWCNTs. This review critically evaluates 93 CNF-based composites tested in the X-band frequency range (8.2-14.2 GHz), focusing on how the microstructural design, filler configuration, and interfacial synergy govern four key performance parameters: shielding effectiveness, electrical conductivity, Joule heating response, and tensile strength. The analysis revealed that achieving high EMI shielding performance is not solely dependent on electrical conductivity, but rather on precise structural architectures, such as layered, gradient, or biomimetic designs, and robust interfacial bonding. Several systems demonstrate shielding effectiveness values exceeding 60 dB at film thicknesses below 0.05 mm, electrical conductivity above 10⁴ S·cm^-1, efficient Joule heating under low voltages (<3 V), and tensile strength exceeding 600 MPa. These findings reinforce the transformative role of CNF as an active structural component in optimizing multifunctional performance. In addition to summarizing recent technical achievements, this article outlines strategic future directions such as the integration of green synthesis methods, scalable fabrication strategies, and adaptive material designs for next-generation EMI shielding systems. Therefore, this review is essential as a comprehensive reference that bridges the gap between the fundamental understanding and practical applications of CNF-based materials, offering a scientific foundation for the development of sustainable, multifunctional, and application-ready EMI shielding solutions.