Construction of heterogeneous wave-absorbing structures inspired by the structure of cucumbers

Abstract

One-dimensional carbon nanofibers (CNFs) hold great potential as lightweight microwave absorbers, mainly attributed to their remarkable plasticity and stability. However, high electrical conductivity unfortunately results in significant surface reflection of microwaves, which limits the application of CNFs. Herein, this research innovatively prepared cucumber-shaped multi-channel CNFs (MC-CNFs-X). By adopting a sacrificial template method, carbon nanotubes (CNTs) and metal particles were successfully incorporated into the structure. The formed heterogeneous interfaces between MC-CNFs-X, CNTs, and metal particles effectively boost dielectric loss. Meanwhile, the multi-channel and heterogeneous structures enhance the scattering of microwaves. Notably, the microstructural characteristics and microwave absorption (MA) performance of the materials can be meticulously tuned by merely modulating the carbonization temperature. In particular, at a carbonization temperature of 1100 °C, MC-CNFs-1100 demonstrates outstanding impedance matching properties and robust MA capabilities. Impressively, at 2.5 mm, the minimum reflection loss (RL_min) value reaches −52.26 dB, and an effective absorption bandwidth (EAB) of 4 GHz can be accomplished under 1.4 mm. These findings lay the groundwork for high-performance lightweight microwave absorbing materials (MAMs).