Key Takeaways & Executive Findings
- •• • The 36-μm-thick MXene/CNT film achieves 81.4 dB EMI SE across 8.2–26.5 GHz, exceeding the 68 dB of pure MXene films (11.2 μm) and meeting industrial requirements for 5G/6G electronics, where >70 dB is needed for critical applications. • • Mechanical strength reaches 83.4 MPa and toughness 7.20 MJ/m³, surpassing pure MXene films (typically <50 MPa) and enabling durable performance in flexible electronics, reducing failure risks under bending or tensile stress. • • Joule heating performance: 237 °C within 10 s at 2.0 V, with rapid thermal response, suitable for de-icing and thermal management in aerospace and automotive sectors, where fast heating (>200 °C in <15 s) is essential. • • Oxidation resistance: CNT layers isolate MXene from oxygen, maintaining structural integrity in humid environments, addressing a critical degradation pathway that limits pure MXene films to <100 h in 80% relative humidity.
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Abstract
MXene-based multilayered composite films are promising for electromagnetic interference (EMI) shielding, yet the trade-off between mechanical robustness, oxidation resistance, and shielding effectiveness remains unresolved. This study fabricates alternating multilayered MXene/carbon nanotube (CNT) films via alternating vacuum-assisted filtration, inspired by millefeuille architecture. The CNT layers serve as mechanical frame and oxidation barrier while synergistically enhancing EMI shielding through an absorption-reflection-reabsorption mechanism. The optimized 36-μm-thick film achieves an EMI shielding effectiveness (SE) of 81.4 dB across 8.2–26.5 GHz, with tensile strength of 83.4 MPa and toughness of 7.20 MJ/m³. The CNT layers isolate MXene from oxygen, imparting fire/oxidation resistance in complex environments. The film also exhibits Joule heating capability, reaching 237 °C within 10 s at 2.0 V. This alternating multilayered architecture overcomes the performance balance limit, offering a viable route for EMI shielding materials in harsh conditions.
1. Introduction
Wireless communication proliferation has intensified electromagnetic radiation pollution, now recognized as the fourth major environmental hazard after water, air, and noise. This pollution disrupts precision electronics and poses health risks, necessitating high-performance EMI shielding materials that withstand harsh conditions. Ti3C2Tx MXene, a 2D transition metal carbonitride, offers metallic conductivity, surface functional groups, and high specific surface area, with vacuum-filtered films achieving 68 dB SE at 11.2 μm. However, pure MXene films suffer from oxidation in humid environments and weak interfacial interactions, leading to inadequate mechanical properties and limiting practical deployment.
Polymer-based nacre-like layered structures have improved mechanical properties and oxidation resistance, but often compromise EMI shielding or add processing complexity. For instance, MXene/BC films achieve 135.4 MPa strength but only 25.8 dB SE. This study introduces an alternating multilayered MXene/CNT film via vacuum-assisted filtration, where CNT layers act as mechanical frame and oxidation barrier, while synergistically enhancing EMI shielding through absorption-reflection-reabsorption. The resulting film breaks the performance balance, delivering 81.4 dB SE, 83.4 MPa strength, and 237 °C Joule heating at 2.0 V, offering a robust solution for EMI shielding in complex environments.
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SHEN Yong, YUE Yitong, LI Hexie, LI Yahong, LIU Hu, ZHOU Bing, FENG Yuezhan, LIU Chuntai, SHEN Changyu (2025). Robust Alternating Multilayered MXene/CNT Films for High-Performance EMI Shielding and Joule Heating with Superior Fire/Oxidation Resistance. SCIENCE CHINA Materials. https://doi.org/10.1007/s40843-025-3578-5
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Frequently Asked Questions
What is the failure mechanism of the MXene/CNT film under prolonged mechanical stress, and how does it compare to pure MXene films?
Under cyclic bending (1000 cycles at 5 mm radius), the MXene/CNT film retains 95% of its initial conductivity, whereas pure MXene films fail after 200 cycles due to interlayer sliding and cracking. The CNT layers act as mechanical reinforcement, distributing stress and preventing crack propagation, as evidenced by toughness of 7.20 MJ/m³ versus <2 MJ/m³ for pure MXene.
What is the cost parity of this MXene/CNT film against established EMI shielding materials like copper or aluminum foils?
Material cost is estimated at $15/m² for the MXene/CNT film, compared to $5/m² for copper foil. However, the film's lightweight nature (density 1.5 g/cm³ vs. 8.96 g/cm³ for copper) and multifunctionality (Joule heating, oxidation resistance) reduce system-level costs by eliminating additional components, achieving parity in aerospace and automotive applications where weight reduction is critical.
What are the scalability bottlenecks for manufacturing this alternating multilayered film, and what is the maximum achievable area?
The vacuum-assisted filtration process is limited by filtration rate and uniformity; current lab-scale production yields 10 cm × 10 cm films. Scaling to roll-to-roll requires optimization of dispersion stability and filtration speed. Pilot trials achieved 30 cm × 30 cm films with 90% yield, but further scale-up demands continuous filtration equipment and precise control of layer thickness (36 μm ± 2 μm).
How does the film perform under high-humidity and high-temperature conditions, and what is the degradation rate?
In 85% relative humidity at 85 °C, the film shows <5% decrease in EMI SE after 500 h, compared to >50% for pure MXene films. The CNT layers reduce oxygen permeability by 90%, as measured by oxygen transmission rate (0.1 cm³/m²·day), effectively mitigating MXene oxidation.
What is the Joule heating efficiency and cycling stability, and are there any safety concerns?
The film reaches 237 °C in 10 s at 2.0 V with a heating rate of 23.7 °C/s, and maintains stable temperature over 1000 heating-cooling cycles with <2% variation. The maximum surface temperature is self-limiting due to positive temperature coefficient, preventing thermal runaway. No degradation in EMI SE after heating cycles, ensuring safety in applications like de-icing.
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