Continuous in-situ growth of carbon nanotubes on carbon fibers at various temperatures for efficient electromagnetic wave absorption

Carbon fiber (CF) has rarely been presented as a promising electromagnetic wave (EMW) absorber because of its excessive electrical conductivity. Herein, the continuous preparation of carbon nanotubes/carbon fiber (CNTs/CF) multiscale reinforcements and microwave absorbers was realized by one-step chemical vapor deposition (CVD) at different temperatures. Beneficial from the intertwined CNTs, good graphitization and crystallinity, and satisfactory epoxy resin wettability, CNTs/CF650 and its composites show excellent tensile, interfacial and interlaminar shear strength. Importantly, CNTs/CF650 obtains a high-performance EMW absorption ability with a minimum reflection loss (RL min ) of −56.11 dB at 7.36 GHz, and delivers an effective absorption band (EAB) of 3.6 GHz at an ultrathin thickness of 1.18 mm. Notably, CNTs/CF700 exhibits the widest EAB (4.2 GHz) at merely 1.35 mm, basically covering the entire Ku-band. The superior RL min and boosted EAB stem from the synergistic effects of multiple heterointerfaces, enriched defects, proper electronic conductivity, and rational impedance matching. Therefore, the work demonstrates a facile and efficient strategy to develop strong EMW absorbers based on CF with light weight, thin thickness, and high strength.