An Liu#, Hua Qiu#, Xinghan Lu, Hua Guo, Jinwen Hu, Chaobo Liang, Mukun He, Ze Yu, Yali Zhang*, Jie Kong and Junwei Gu*. Asymmetric Structural MXene/PBO Aerogels for High-Performance Electromagnetic Interference Shielding with Ultra-Low Reflection. Advanced Materials, 2024, 10.1002/adma.202414085. 2023IF=27.4

https://onlinelibrary.wiley.com/doi/10.1002/adma.202414085

Abstract

Electromagnetic interference (EMI) shielding materials with low electromagnetic (EM) waves reflection characteristics are ideal materials for blocking EM radiation and pollution. Materials with low reflectivity must be constructed using materials with excellent EM waves absorption properties. However, materials simultaneously possessing both low reflectivity and excellent EMI shielding performance remain scarce, consequently, multilayer structures need to be developed. Poly(p-phenylene–2,6–benzobisoxazole) nanofibers (PNF) are prepared by deprotonation. PNF are combined with MXene and heterostructure MXene@Ni prepared by in-situ growth; MXene@Ni/PNF acts as an EM absorption layer while the MXene/PNF acts as an EM reflective layer. Finally, (MXene@Ni/PNF)–(MXene/PNF) aerogels are prepared by layer-by-layer freeze-drying based on the layered modular design concept. Experimental characterizations revealed that (MXene@Ni/PNF)–(MXene/PNF) aerogels enable the efficient absorption-reflection-reabsorption of EM waves, effectively eliminating EMI. When the mass ratio of MXene to Ni in MXene@Ni is 1:6 and the mass fraction of MXene in the reflective layer is 80 wt%, the (MXene@Ni/PNF)–(MXene/PNF) aerogels exhibit excellent EMI shielding performance (71 dB) and a very low reflection coefficient (R = 0.10). Finite element simulations verified that the developed asymmetric structural aerogels achieve high EMI shielding performance with low reflection characteristics. In addition, (MXene@Ni/PNF)–(MXene/PNF) aerogels display excellent infrared camouflage ability.

具有低反射特性的电磁屏蔽材料是防止电磁辐射和电磁污染的理想材料，要想实现电磁屏蔽材料的低反射特性，需要引入吸收层使材料具有优异的电磁波吸收性能。但是如何合理地设计吸收层与反射层，并将两者实现高效的集成是一个亟需解决的问题。本文采用去质子化法制备聚对苯撑苯并二噁唑纳米纤维（PNF），借助原位生长法、通过“静电吸附-溶剂热还原”制备异质结构MXene@Ni电磁功能填料，以PNF为基体，MXene与MXene@Ni为填料，基于分层模块设计理念，经逐层冷冻干燥技术制备(MXene@Ni/PNF)-(MXene/PNF)气凝胶。得益于吸收层MXene@Ni/PNF与反射层MXene/PNF的协同作用，实现了(MXene@Ni/PNF)-(MXene/PNF)气凝胶对入射电磁波的“吸收-反射-再吸收”过程。当MXene@Ni中MXene与Ni的质量比为1:6、反射层MXene/PNF中MXene质量分数为80 wt%时，该气凝胶在X波段具有优异的电磁屏蔽性能（71 dB）和极低的平均反射系数（0.10）。有限元模拟进一步验证了该气凝胶具有优异的电磁屏蔽性能和低反射特性。此外，(MXene@Ni/PNF)-(MXene/PNF)气凝胶还具有红外伪装的功能。

论文亮点

1. 借助原位生长法、通过“静电吸附-溶剂热还原”在MXene表面原位生长海胆状的磁性Ni纳米颗粒，制备异质结构MXene@Ni电磁功能填料。当MXene与Ni质量比为1:6时，MXene@Ni复合材料在2~3 mm厚度范围内具有良好的阻抗匹配特性（|Zin/Z0|的值更接近于1）。

2. 以聚对苯撑苯并二噁唑纳米纤维（PNF）为基体，MXene与MXene@Ni为填料，基于分层模块设计理念，经逐层冷冻干燥技术制备(MXene@Ni/PNF)-(MXene/PNF)气凝胶。当MXene@Ni中MXene与Ni的质量比为1:6、反射层MXene/PNF中MXene质量分数为80 wt%时，该气凝胶在X波段具有优异的电磁屏蔽性能（71 dB）和极低的平均反射系数（0.10）。

3. 由于MXene的低红外发射率（24.6%）和气凝胶的优异隔热性能（吸收层MXene@Ni/PNF导热系数为0.092 W/(m·K)；反射层MXene/PNF导热系数为0.069 W/(m·K)），(MXene@Ni/PNF)-(MXene/PNF)气凝胶具有优异的红外伪装特性。

第一作者：柳岸、邱华

邮件地址：liuan2000@mail.nwpu.edu.cn、huaqiu@nwpu.edu.cn

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