Pillared amorphous carbon nanotube/MXene nanohybrid for ultrathin broadband electromagnetic wave absorption

The promise of MXenes for high-performance electromagnetic wave (EMW) absorption, driven by their excellent in-plane conductivity, is fundamentally hampered by inefficient interlayer charge transport in multilayer assemblies. To address this, a pillared amorphous carbon nanotube (ACNT)/MXene (PAM) nanohybrid is engineered, wherein ACNTs are grown in situ between MXene interlayers using a modified floating-catalyst chemical vapor deposition (CVD). In this design, the ACNTs are treated not merely as structural pillars, but as critical functional components tailored to fulfill three synergistic roles essential for superior EMW absorption: establishing efficient through-plane conductive pathways, introducing abundant defect-induced polarization centers, and ensuring favorable impedance matching. The resulting PAM nanohybrid achieves a minimum reflection loss of −58.87 dB at 14.48 GHz and a broad effective absorption bandwidth of 4.88 GHz with a thickness of 1.2 mm. Density functional theory (DFT) calculations offer further insight, revealing that the pillared architecture plays a central role in suppressing dielectric anisotropy. This suppression is identified as a critical mechanism for maximizing energy dissipation, which has not been fully exploited in previous studies. Beyond presenting a high-performance material, this work offers a versatile design strategy to mitigate the dimensional limitations of 2D materials, paving the way for advanced functional composites in stealth, sensing, and energy applications.