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.
輕質高效的微波吸波劑在電磁輻射防護領域具有廣闊的應用前景，但仍面臨著巨大的挑戰。本文通過刻蝕-熱解-水熱反應的協同步驟，成功制備了具有分級結構和增強協同效應的中空Co/NC@MnO2（H-Co/ NC@MnO2）多面體。具體而言，帶有雜原子的Co/NC中空結構使多面體具有輕量化特性、偶極極化和磁損耗，含氧空位的分層MnO2納米片賦予介電損耗和多重散射，Co/NC和MnO2之間的介電-磁協同效應促進了阻抗匹配并增強了界面極化。得益于上述優點，H-Co/NC@MnO2多面體在20wt%的低填充量下表現出高效的微波衰減性能。最佳反射損耗達到-54.7 dB，有效吸收帶寬為11.8 GHz至18 GHz（6.2 GHz），厚度僅為2.1 mm。這些研究結果為開發高效、輕量化的微波吸收劑提供了一種有效的制備方案。
論文亮點
1.提出了蝕刻-熱解-水熱反應制備空心Co/NC@MnO2多面體吸波材料的方法，并研究了空心和分層結構對材料的微波吸收性能的協同作用。
2.Co/NC的空心結構有利于傳導損耗，層次化MnO2納米片強化介電損耗并誘發多重散射，且MnO2納米片之間大量的非均質界面能夠產生更強的界面極化。
3.空心Co/NC@MnO2多面體吸波材料在填充量為20%，厚度為2.1 mm時吸波性能最佳，最佳反射損耗為-54.7 dB，有效頻寬達到了6.2 GHz。
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