Hierarchical Cellulose/MXene Aerogel Films with Coral‐Like Polyaniline Skin for Absorption‐Led Broadband EMI Shielding

ABSTRACT Lightweight, absorption‐dominant electromagnetic interference (EMI) shielding films are critical for wearable and portable electronics. However, achieving strong attenuation while maintaining porous architectures and continuous conductive pathways remains challenging. We present a biomimetic hierarchical design in regenerated cellulose/MXene aerogel films featuring a surface‐confined, coral‐like polyaniline (PANI) skin. This structure is created by integrating molten salt hydrate processing with interfacially confined oxidative polymerization. The result is a dual‐interface skin–core architecture: polarization‐active interfaces are concentrated at the outer surface, while a MXene‐rich, porous, and percolated conductive framework is preserved in the interior. The spatially localized PANI growth is governed by confined mass transport in tortuous pores, rapid reactant depletion near the hydrogel–solution interface, and hydrogen‐bond interactions between protonated aniline and regenerated cellulose. This approach enhances interfacial properties without disrupting internal conductive continuity. The interface‐enriched skin, together with the percolated scaffold, suppresses MXene restacking and strengthens absorption‐dominant EMI shielding. The optimized film delivers an electrical conductivity of 2618 S·m ⁻¹ and an average X band shielding effectiveness of 62.3 dB, corresponding to a thickness‐normalized shielding efficiency of 35 600 dB·cm ² ·g ⁻¹ . Additionally, the film exhibits broadband shielding across X/Ku/K/Ka bands and retains performance after 1 year of storage, highlighting structural robustness and practical potential for EMI shielding applications.