In situ growth of carbon nanotubes on MXenes for high-performance electromagnetic wave absorption

Two-dimensional transition metal carbides and nitrides (MXenes), especially titanium carbide, are ideal materials for high-performance microwave absorbers. Nonetheless, their characteristics of being prone to stacking and agglomeration seriously affect their application. Moreover, their elevated electrical conductivity results in the reflection of electromagnetic waves (EMW) rather than their absorption. This study proposes a simple strategy to grow CNTs on the surface of MXenes by chemical vapor deposition (CVD) technology, and introduces a SiO₂ intermediate layer to uniformly distribute CNTs on the substrate surface. Controlling the growth of CNTs by adjusting the reaction time to regulate the microstructure and electromagnetic parameters of the composite materials, the wave absorption performance under low filling amount was significantly improved. MXene@SiO₂-CNTs exhibit a minimum reflection loss of -48.38 dB at a thickness of 2.1 mm, with an effective absorption bandwidth extending to 5.47 GHz (from 12.53 GHz to 18 GHz). The radar cross-section values of MXene@SiO₂-15CNTs are all below -15 dBm², significantly diminishing the likelihood of radar detection of the target.