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<p>With the rapid advancement of electronic communication technologies, electromagnetic pollution and interference from various electronic devices pose risks to both the environment and human health. As a result, research on electromagnetic shielding materials is intensifying. New electromagnetic shielding materials can be produced cost-effectively using biomass carbon materials. This study prepared corn cob-based carbon materials at 700 °C using four methods: direct carbonization, KOH-activated carbonization, Fe<sup>3⁺</sup>/Fe<sup>2⁺</sup> impregnation carbonization, and a combined KOH activation Fe<sup>3⁺</sup>/Fe<sup>2⁺</sup> impregnation method. The combined-method material exhibited the best overall electromagnetic shielding performance among all the carbon materials. The carbon powder, with a thickness of 1.1 mm, showed the lowest reflection loss of − 26.63 dB at 3.09 GHz, with a − 15 dB bandwidth of 1.85 GHz. Regarding shielding effectiveness, the material maintained a value below − 15 dB across the 1–6 GHz range, with a − 20 dB bandwidth of 2.14 GHz. The minimum value of − 34.17 dB occurred at 2.64 GHz. Compared to the directly carbonized sample, the sample carbonized using the combined method effectively combined the pore-forming capability of KOH activation with the magnetic loss from Fe<sub>3</sub>O<sub>4</sub> nanoparticles. The electromagnetic shielding and absorption performance of the combined-method material was well explained by its electromagnetic parameters, particularly the total electromagnetic loss tangent.</p>

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Preparation of carbon materials from corn cobs and performance in reflection loss and electromagnetic shielding

  • 期刊论文

  • 发表日期：

    2025年12月14日

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  • Jia Yang,
  • Baoli Shi

摘要

With the rapid advancement of electronic communication technologies, electromagnetic pollution and interference from various electronic devices pose risks to both the environment and human health. As a result, research on electromagnetic shielding materials is intensifying. New electromagnetic shielding materials can be produced cost-effectively using biomass carbon materials. This study prepared corn cob-based carbon materials at 700 °C using four methods: direct carbonization, KOH-activated carbonization, Fe3⁺/Fe2⁺ impregnation carbonization, and a combined KOH activation Fe3⁺/Fe2⁺ impregnation method. The combined-method material exhibited the best overall electromagnetic shielding performance among all the carbon materials. The carbon powder, with a thickness of 1.1 mm, showed the lowest reflection loss of − 26.63 dB at 3.09 GHz, with a − 15 dB bandwidth of 1.85 GHz. Regarding shielding effectiveness, the material maintained a value below − 15 dB across the 1–6 GHz range, with a − 20 dB bandwidth of 2.14 GHz. The minimum value of − 34.17 dB occurred at 2.64 GHz. Compared to the directly carbonized sample, the sample carbonized using the combined method effectively combined the pore-forming capability of KOH activation with the magnetic loss from Fe3O4 nanoparticles. The electromagnetic shielding and absorption performance of the combined-method material was well explained by its electromagnetic parameters, particularly the total electromagnetic loss tangent.