MXene as conductive mortar: Assembly of Ti3C2Tx and carbon nanotube fibers into multifunctional films for EMI shielding and infrared stealth

Abstract

Advanced electronic and defense systems require multifunctional films that combine electromagnetic interference (EMI) shielding and infrared (IR) stealth with mechanical robustness, high electrical conductivity, and low IR emissivity. Here, we report a mechanically strong and highly conductive Ti3C2Tx/CNT hybrid film with a hierarchical brick-and-mortar (B-M) structure, fabricated through a simple and scalable assembly of Ti3C2Tx-coated CNT fibers into a continuous film without complex weaving or post-processing. In this structure, the Ti3C2Tx nanosheets act as conductive “mortar” between CNT fiber (CNTF) “bricks,” forming efficient two-dimensional conductive pathways while suppressing inter-fiber slippage. As a result, the hybrid film achieves a high electrical conductivity of 9,236 S cm-1 and a tensile strength of 1.02 GPa. Owing to its excellent electrical conductivity, the film achieves an average EMI shielding effectiveness (SE) of 92.8 and 97.4 dB in the X- and Ka-band with a thickness of only 17.5 μm, respectively. The hybrid film maintains long-term stability of its strength, electrical conductivity, and EMI SE under diverse environmental conditions. In addition, the conformal low-emissivity Ti3C2Tx coating enables effective IR stealth performance across a broad temperature range from room temperature to 300 °C. This work provides a strategic design for multifunctional shielding materials, offering a viable path for the next generation of high-performance stealth and communication technologies. A continuous assembly strategy integrates amine-functionalized carbon nanotube fibers as structural “bricks” with Ti3C2Tx MXene as a conductive “mortar,” enabling scalable fabrication of a multifunctional hybrid film. The brick-and-mortar architecture facilitates efficient load transfer and establishes two-dimensional conductive pathways, yielding a tensile strength of 1.02 GPa and an electrical conductivity of 9,236 S/cm. The resulting hybrid film achieves an exceptional EMI shielding effectiveness of 92.8 and 97.4 dB in the X- and Ka-band with a thickness of only 17.5 μm, respectively, alongside infrared stealth capability through the intrinsically low-emissivity MXene surface layer.