In-Situ Grown Carbon Nanotube-Reinforced Wood-Derived Carbon Composites with Magnetic-Dielectric Synergy for High-Efficiency and Broadband Electromagnetic Wave Absorption

The development of high-performance electromagnetic wave (EMW) absorbers that integrate strong absorption, broad bandwidth, minimal thickness, and lightweight characteristics remains a significant challenge. Wood-derived carbon (CW), with its innate hierarchical porous structure, presents a promising sustainable platform; however, its limited dielectric loss often restricts its absorption performance. Herein, we report an eco-friendly strategy to fabricate lightweight carbon nanotubes (CNTs)-reinforced wood-derived carbon composites (CNT-CW) via chemical vapor deposition (CVD). Natural balsa wood is carbonized to retain its honeycomb porous structure, followed by in situ growth of CNTs within the channels using Ni as a catalyst and melamine as a carbon source. The unique structure optimizes EMW propagation paths, while the synergistic effect between magnetic Ni nanoparticles and dielectric CNTs enhances interfacial polarization and magnetic-dielectric losses. The optimized CNT-CW achieves a minimum reflection loss (RL) of -55.5 dB at 2.3 mm thickness and an ultrawide effective absorption bandwidth (EAB) of 5.87 GHz at 1.7 mm. Moreover, it exhibits rapid electrothermal response (20 s to 89 °C at 5 V) and excellent thermal stability. This work demonstrates a sustainable route to high-performance EMW absorbers using biomass-derived architectures.