Dual-Doped Polyaniline Boosting the Construction of Fireproof MXene/Aramid Nanofiber Films for Superior Electromagnetic Interference Shielding and On-Demand Joule Heating

The rapid advancement of portable electronics and wireless communication technologies has intensified electromagnetic pollution, creating a pressing need for lightweight, flexible, and safe electromagnetic interference (EMI) shielding materials. In this study, we developed a mechanically robust and flexible composite film by integrating MXene into an aramid nanofiber (ANF) matrix with dual-doped polyaniline (DPANI)-encapsulated MXene nanohybrids (MXene–DPANI, codoped with phytic acid and copper ions). The resulting ANF/MXene/MXene–DPANI (AMP) films exhibited high tensile strength, accompanied by superior fire resistance. Systematic evaluation revealed the superior EMI shielding performance of AMP films in the X-band range (8.2–12.4 GHz). Remarkably, a 30 μm-thick film with a 1:1 filler ratio of MXene to MXene–DPANI achieved an impressive EMI shielding effectiveness (SE) of 31 dB, surpassing commercial benchmarks. Further increasing the film thickness to 70 μm enhanced the EMI SE to 35 dB. Furthermore, optimizing the filler ratio to 3:1 (MXene:MXene–DPANI) significantly improved the EMI SE to 40 dB (30 μm thickness). The AMP films also displayed a controllable Joule heating performance, attaining a stable temperature of over 76 °C at 6 V with outstanding cycling stability. These findings underscore the potential of MXene-based nanofiller-decorated ANF composite films as high-performance EMI shielding materials for multifunctional applications.