Regulating the Structure\nof Single-Walled Carbon Nanohorns\nfor Impedance Matching and Electromagnetic Wave Absorption

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