Three-dimensional bamboo-like amorphous N/S co-doped carbon nanotubes encapsulated with Cu nanoparticles/carbon fiber heterostructures for boosting electromagnetic wave absorbing properties

Highly efficient and multifunctional electromagnetic wave (EMW) absorbers which can be easily processed are desirably required. Herein, cupric ammonia is creatively adopted as the catalyst precursor of the in-situ growth of carbon nanotubes (CNTs) onto carbon fiber (CF) during chemical vapor deposition. Typically, when prepared at 750 °C, N/S co-doped bamboo-like amorphous CNTs/CF was successfully synthesized, while some Cu nanoparticles were remained in CNT forests. The sample obtains an excellent absorption toward EMWs, demonstrating a minimal reflection loss of −59.28 dB at 14.1 GHz with an ultrathin thickness of 1.42 mm. Concurrently, it is over a relatively broad effective absorption bandwidth (EAB) of 3.3 GHz (12.3–15.6 GHz) with 31% loading in the paraffin matrix. And the EAB value of CA-700 reaches 3.7 GHz (14.3–18 GHz) at merely 1.45 mm. The satisfying attenuation performance mainly originates from the synergistic effects of continuous three-dimensional conducting networks, abundant interfaces, sufficient defects, and the well impedance matching. Moreover, all as-prepared samples could be potentially used as reinforcements of resin matrix composites with high strength. Therefore, a facile route is provided to produce thin, lightweight, superior and high-strength EMW absorbing materials based on CF and CNTs.