School of Materials Science and Engineering, Beihang University , Beijing 100191, China.
Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, China.
ACS Appl Mater Interfaces. 2017 Sep 13;9(36):30850-30861. doi: 10.1021/acsami.7b10067. Epub 2017 Aug 28.
Developing lightweight and highly efficient electromagnetic wave (EMW) absorbing materials is crucial but challenging for anti-electromagnetic irradiation and interference. Herein, we used multiwalled carbon nanotubes (MWCNTs) as templates for growth of Co-based zeolitic imidazolate frameworks (ZIFs) and obtained a Co-C/MWCNTs composite by postpyrolysis. The MWCNTs interconnected the ZIF-derived Co-C porous particles, constructing a conductive network for electron hopping and migration. Moreover, the Co-C/MWCNTs composite was aligned in paraffin matrix under an external magnetic field, which led to a stretch of the MWCNTs along the magnetic field direction. Due to the anisotropic permittivity of MWCNTs, the magnetic alignment considerably increased the dielectric loss of the Co-C/MWCNTs composite. Benefiting from the conductive network, the orientation-enhanced dielectric loss, and the synergistic effect between magnetic and dielectric components, the magnetically aligned Co-C/MWCNTs composite exhibited extremely strong EMW absorption, with a minimum reflection loss (RL) of -48.9 dB at a filler loading as low as 15 wt %. The specific RL value (RL/filler loading) of the composite was superior to that of the previous MOF-derived composite absorbers. It is expected that the proposed strategy can be extended to the fabrication of other lightweight and high-performance EMW-absorbing materials.
开发轻量且高效的电磁波（EMW）吸收材料对于抗电磁辐射和干扰至关重要，但极具挑战性。在此，我们以多壁碳纳米管（MWCNTs）为模板，生长钴基沸石咪唑酯骨架（ZIFs），并通过后热解得到 Co-C/MWCNTs 复合材料。MWCNTs 相互连接 ZIF 衍生的 Co-C 多孔颗粒，构建电子跳跃和迁移的导电网络。此外，在外部磁场下，Co-C/MWCNTs 复合材料在石蜡基体中排列，导致 MWCNTs 沿磁场方向伸展。由于 MWCNTs 的各向异性介电常数，磁定向极大地增加了 Co-C/MWCNTs 复合材料的介电损耗。得益于导电网络、取向增强的介电损耗以及磁和介电组件的协同效应，定向排列的 Co-C/MWCNTs 复合材料表现出极强的 EMW 吸收能力，在填充量低至 15wt%时，最小反射损耗（RL）为-48.9dB。该复合材料的特定 RL 值（RL/填充量）优于之前的 MOF 衍生复合吸收剂。预计所提出的策略可以扩展到制造其他轻量且高性能的 EMW 吸收材料。
