Carbon nanotubes (CNT) are among the strongest candidates for electromagnetic interference (EMI) shielding materials because of their excellent performance. However, when assembled into macroscale materials, their conductivity is usually limited to 104 S/m, restricting further application as shielding materials. Here, we prepared a carbon nanotube composite film (Au/Cl-CNT) with high conductivity and excellent EMI properties. Characterizations confirm that Au exists in the form of uniform Au plates and particles anchored on the CNT surface, while Cl is doped into the CNT framework as halogen dopants. The optimized Au/Cl-CNT film delivers an ultra-high electrical conductivity of 3.39 × 105 S/m, which is approximately 23 times higher than that of the pristine CNT film. The excellent electrical properties of the Au/Cl-CNT films endow them with excellent EMI shielding effectiveness (SE). Au/Cl-CNT films with a thickness of ~10.5 μm achieve an EMI SE of up to 67 dB across both the X-band and Ku-band. The superior EMI SE mainly results from the combined effect of various mechanisms, namely reflection inside and outside the material, as well as absorption inside the material. This work clarifies the synergistic enhancement mechanism of Au and Cl on CNT conductivity and EMI shielding, offering new insights into halogen-modified shielding materials.
Mao et al. (Mon,) studied this question.