Novel cable-like tin@carbon whiskers derived from the Ti2SnC MAX phase for ultra-wideband electromagnetic wave absorption

One-dimensional (1D) metals are well known for their exceptional conductivity and their ease of formation of interconnected networks that facilitate electron migration, making them promising candidates for electromagnetic (EM) attenuation. However, the impedance mismatch from high conductivity and their singular mode of energy loss hinder effective EM wave dissipation. Construction of cable structures not only optimizes impedance matching but also introduces a multitude of heterojunctions, increasing attenuation modes and potentially enhancing EM wave absorption (EMA) performance. Herein, we showcase the scalable synthesis of tin (Sn) whiskers from a Ti₂SnC MAX phase precursor, followed by creation of a 1D tin@carbon (Sn@C) cable structure through polymerization of PDA on their surface and annealing in argon. The EMA capabilities of Sn@C significantly surpass those of uncoated Sn whiskers, with an effective absorption bandwidth reaching 7.4 GHz. Remarkably, its maximum radar cross section reduction value of 27.85 dB m² indicates its exceptional stealth capabilities. The enhanced EMA performance is first attributed to optimized impedance matching, and furthermore, the Sn@C cable structures have rich SnO₂/C and Sn/SnO₂ heterointerfaces and the associated defects, which increase interfacial and defect-induced polarization losses, as visually demonstrated by off-axis electron holography. The development of the Sn@C cable structure represents a notable advancement in broadening the scope of materials with potential applications in stealth technology, and this study also contributes to the understanding of how heterojunctions can improve EMA performance.