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<p>High-performance electromagnetic wave (EMW) absorbers are urgently needed for the increasingly serious electromagnetic radiation problem. Hollow porous carbon structures are ideal lightweight EMW absorber materials. However, carbon materials often have suboptimal EMW absorption properties due to the lack of sufficient polarization centers. In this paper, samples of hollow carbon cubits (HCCs) absorbers at different temperatures were prepared by coating and pyrolysis processes using NaCl as a template and introducing elemental N during the synthesis of the carbon source. The effect of the introduction of N elements at different graphitization levels was investigated by analyzing the microscopic morphology and electromagnetic parameters of the samples at different temperatures. The results show that the graphitization degree of the HCCs gradually deepens with the increase of pyrolysis temperature, and compared with other samples, the excellent impedance matching of the HCCs at 700&#xa0;°C leads to the outstanding electromagnetic wave absorption performance, which is further enhanced by the dipole polarization brought by the N element contained in the shell layer. Specifically, the maximum reflection loss reaches − 36.8&#xa0;dB with an effective absorption bandwidth of 4.6&#xa0;GHz (10.5–15.1&#xa0;GHz) at a loading rate of 10&#xa0;wt% and a composite thickness of 2.5&#xa0;mm. Therefore, the electromagnetic wave absorption properties of phenolic resins can be effectively enhanced by varying their carbonation temperature and by introducing multiple polarizations brought about by N elements.</p>

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Preparation of high-performance EMW absorbing materials by the HCCs at different temperatures

  • 期刊论文

  • 发表日期：

    2025年6月14日

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  • Chaoqun Yang,
  • Chenyu Zhu,
  • Yingying Zhou,
  • Haonan Du,
  • Yuanyuan Lu,
  • Man Yu,
  • Shiping Tao,
  • Hui Xie

摘要

High-performance electromagnetic wave (EMW) absorbers are urgently needed for the increasingly serious electromagnetic radiation problem. Hollow porous carbon structures are ideal lightweight EMW absorber materials. However, carbon materials often have suboptimal EMW absorption properties due to the lack of sufficient polarization centers. In this paper, samples of hollow carbon cubits (HCCs) absorbers at different temperatures were prepared by coating and pyrolysis processes using NaCl as a template and introducing elemental N during the synthesis of the carbon source. The effect of the introduction of N elements at different graphitization levels was investigated by analyzing the microscopic morphology and electromagnetic parameters of the samples at different temperatures. The results show that the graphitization degree of the HCCs gradually deepens with the increase of pyrolysis temperature, and compared with other samples, the excellent impedance matching of the HCCs at 700 °C leads to the outstanding electromagnetic wave absorption performance, which is further enhanced by the dipole polarization brought by the N element contained in the shell layer. Specifically, the maximum reflection loss reaches − 36.8 dB with an effective absorption bandwidth of 4.6 GHz (10.5–15.1 GHz) at a loading rate of 10 wt% and a composite thickness of 2.5 mm. Therefore, the electromagnetic wave absorption properties of phenolic resins can be effectively enhanced by varying their carbonation temperature and by introducing multiple polarizations brought about by N elements.