Chenhao Wei, Mukun He, Maoqing Li*, Xiao Ma, Wenlong Dang, Panbo Liu and Junwei Gu*. Hollow Co/NC@MnO2 polyhedrons with enhanced synergistic effect for high-efficiency microwave absorption. Materials Today Physics, 2023, 36: 101142. 2022IF=11.5.
https://doi.org/10.1016/j.mtphys.2023.101142
Abstract
High-efficiency microwave absorbents with lightweight characteristics possess prospective applications in electromagnetic radiation protection, but still face huge challenges. Herein, hollow Co/NC@MnO2 (H–Co/NC@MnO2) polyhedrons with hierarchical structure and enhanced synergistic effect are successfully fabricated via the collaborative steps of etching-pyrolysis-hydrothermal reaction. Specifically, hollow engineering of Co/NC with heteroatoms endow the polyhedrons with lightweight characteristics, dipolar polarization and magnetic loss, hierarchical MnO2 nanosheets with oxygen vacancies grant dielectric loss and multiple scattering, and the dielectric-magnetic synergistic effect between Co/NC and MnO2 promote impedance matching and strengthen interfacial polarization. Benefiting from the above mentioned advantages, the H–Co/NC@MnO2 polyhedrons exhibit high-efficiency microwave attenuation at a low filler loading of 20 wt%. The optimal reflection loss reaches -54.7 dB and the effective absorption bandwidth ranges from 11.8 GHz to 18 GHz (6.2 GHz) with a thickness of only 2.1 mm. These findings provide us a promising strategy in developing high-efficiency and lightweight microwave absorbents for practical applications.
轻质高效的微波吸波剂在电磁辐射防护领域具有广阔的应用前景，但仍面临着巨大的挑战。本文通过刻蚀-热解-水热反应的协同步骤，成功制备了具有分级结构和增强协同效应的中空Co/NC@MnO2（H-Co/ NC@MnO2）多面体。具体而言，带有杂原子的Co/NC中空结构使多面体具有轻量化特性、偶极极化和磁损耗，含氧空位的分层MnO2纳米片赋予介电损耗和多重散射，Co/NC和MnO2之间的介电-磁协同效应促进了阻抗匹配并增强了界面极化。得益于上述优点，H-Co/NC@MnO2多面体在20wt%的低填充量下表现出高效的微波衰减性能。最佳反射损耗达到-54.7 dB，有效吸收带宽为11.8 GHz至18 GHz（6.2 GHz），厚度仅为2.1 mm。这些研究结果为开发高效、轻量化的微波吸收剂提供了一种有效的制备方案。
论文亮点
1.提出了蚀刻-热解-水热反应制备空心Co/NC@MnO2多面体吸波材料的方法，并研究了空心和分层结构对材料的微波吸收性能的协同作用。
2.Co/NC的空心结构有利于传导损耗，层次化MnO2纳米片强化介电损耗并诱发多重散射，且MnO2纳米片之间大量的非均质界面能够产生更强的界面极化。
3.空心Co/NC@MnO2多面体吸波材料在填充量为20%，厚度为2.1 mm时吸波性能最佳，最佳反射损耗为-54.7 dB，有效频宽达到了6.2 GHz。
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