Regulating the Structure of Single-Walled Carbon Nanohorns for Impedance Matching and Electromagnetic Wave Absorption

Although single-walled carbon nanohorns (SWCNHs) are dielectric nanoabsorbers for efficiently absorbing electromagnetic waves (EMWs), to the best of our knowledge, previous studies have neglected to investigate the intrinsic EMW absorptions of SWCNHs. Therefore, in this study, to clarify the EMW absorptions of different aggregation structures, helium arc plasma was used to regulate the structure of dahlia-, bud-, and seed-like (D-, B-, and S-) SWCNHs. Because of rich defects, large specific surface areas, and abundant pores provided by numerous horn structures on the D-SWCNH surface, D-SWCNHs possess impedance matching and loss capabilities superior to those of B-SWCNHs and S-SWCNHs. Furthermore, the conductive network formed by the cross-linked horn structures generates eddy current losses, further increasing the EMW loss capacity of D-SWCNHs. Overall, because of the abundant horn structure, SWCNHs possess excellent EMW absorption without using any magnetic materials. D-SWCNHs possess excellent EMW absorption, where the reflection loss (RL) and effective absorption bandwidth (EAB) reach 50.14 dB and 5.3 GHz at thicknesses of only 1.55 and 1.77 nm, respectively. Below −10 dB, the RL curve can cover 89.4% of the measurement frequency range (3.7–18 GHz). This work provides a strategy for fabricating pure carbon EMW absorbers, and D-SWCNHs are prospective candidates for developing lightweight high-performance EMW-absorbing nanomaterials.