Owing to their unique electromagnetic properties and structure anisotropy, two-dimensional (2D) magnetic metal flakes are attracting special attention for applications as microwave absorption materials. However, the conductive network formed by the connected metal flakes may lead to impedance mismatching and reduced performance. In this study, a facile and rational strategy was developed to fabricate yolk–shell-structured 2D flaky Fe/void/C composites by using α-Fe₂O₃ hexagonal flakes as the template, followed by the coating of polydopamine (PDA) on the composite surface and calcination under H₂/Ar. The volume shrinkage from Fe₂O₃ to Fe and PDA to carbon led to the formation of several irregular holes in Fe flakes and void space between the Fe cores and carbon cages. The thickness of carbon cages of the composites can be tailored by the simple modulation of the synthetic parameters. As a result of the synergistic effects of multiple chemical components, the shape anisotropy of iron flakes, and unique yolk–shell structures, the optimized sample exhibited excellent microwave absorption properties. With a matching thickness of only 1.6 mm, the strongest reflection loss (RL) was up to −27.80 dB at 14.72 GHz, and the effective absorption bandwidth (EAB, RL < −10 dB) reached 6.40 GHz (11.60–18.00 GHz), which can cover the whole Ku-band. This study provides a novel approach to adjust and balance the permeability and permittivity of 2D magnetic metal flakes, which may promote the practical applications of flaky magnetic metal materials in microwave absorption.

中文翻译：

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用于增强微波吸收性能的二维片状 Fe/void/C 复合材料的合理设计

由于其独特的电磁特性和结构各向异性，二维（2D）磁性金属薄片作为微波吸收材料的应用受到了特别关注。然而，由连接的金属薄片形成的导电网络可能导致阻抗失配和性能下降。_{在本研究中，以α-Fe 2} O ₃六方薄片为模板，然后在表面涂覆聚多巴胺（PDA），开发了一种简便合理的策略来制备蛋黄壳结构的二维片状Fe/void/C复合材料。 H ₂ /Ar下的复合表面和煅烧。Fe ₂ O _{3的体积收缩}到 Fe 和 PDA 到碳导致在 Fe 薄片中形成几个不规则的孔以及 Fe 核心和碳笼之间的空隙空间。复合材料的碳笼的厚度可以通过合成参数的简单调节来定制。由于多种化学成分的协同作用、铁片的形状各向异性和独特的蛋黄壳结构，优化后的样品表现出优异的微波吸收性能。匹配厚度仅为 1.6 mm，在 14.72 GHz 时最强反射损耗（RL）高达 -27.80 dB，有效吸收带宽（EAB，RL < -10 dB）达到 6.40 GHz（11.60-18.00 GHz），可以覆盖整个Ku波段。本研究提供了一种调节和平衡二维磁性金属薄片的磁导率和介电常数的新方法，