In situ synthesis of hierarchical rose-like porous Fe@C with enhanced electromagnetic wave absorption
In situ synthesis of hierarchical rose-like porous Fe@C with enhanced electromagnetic wave absorption
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DOI：
10.1039/c7tc04897a
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发表时间：
2018-01-21
影响因子：
6.4
通讯作者：
Xu, Zhaopeng
中科院分区：
文献类型：
--
作者：
Li, Xueai;Du, Daxue;Xu, Zhaopeng
为了满足高性能电磁波吸收器的要求，需要设计形态和丰富界面的碳-铁磁金属复合材料来平衡阻抗匹配和衰减。然而，满足这些要求的复合材料的合成和电磁波能量损失机理的分析仍然存在很大的挑战。在本研究中，利用具有玫瑰状形态的醇氧化铁前驱体，通过原位途径成功合成了具有多孔结构的层次化玫瑰状碳包铁纳米颗粒（Fe@C）。在研究的热解气氛和温度下，玫瑰样Fe@C和纯铁可以很好地调节。由于铁纳米粒子的催化作用，碳壳呈石墨状且高度有序，从而影响了复合材料的电磁性能。在2.0 ~ 18.0 GHz的频率范围内，对Fe@C复合材料和铁的电磁波吸收特性进行了估计，结果表明，层次化玫瑰状多孔Fe@C具有出色的反射损耗特性，最小值为-71.47 dB，匹配薄厚度为1.48 mm。实现了2.88 ~ 18.0 GHz的超宽响应带宽（反射损耗小于-10 dB）。电磁特性分析表明，层次状玫瑰状Fe@C粒子的电磁功能与纯铁粒子和未由相同结构的醇氧化铁前驱体衍生出玫瑰状结构的Fe@C粒子相比有很大的不同。具有一定微观结构的碳壳和特殊形态可以有效调节复合介电常数和磁导率，改变阻抗匹配特性，增强电磁波在层次化玫瑰状Fe@C颗粒中的多次反射和散射衰减能力。对衰减常数和匹配特性阻抗的分析验证了具有多孔结构的玫瑰状Fe@C的电磁波吸收增强是由于匹配阻抗和集体多重损耗机制的显著增强。
To satisfy the requirements of high-performance electromagnetic wave absorbers, composites of carbon and ferromagnetic metal with designed morphologies and abundant interfaces are highly desirable to balance impedance matching and attenuation. However, the synthesis of composites to meet these requirements and analysis of the electromagnetic wave energy loss mechanism remain great challenges. In this study, hierarchical rose-like assemblies of carbon-wrapped iron (Fe@C) nanoparticles with a porous structure were successfully synthesized via an in situ route using an iron alkoxide precursor with a rose-like morphology. Under the studied pyrolysis atmosphere and temperature, rose-like Fe@C and pure iron can be well modulated. The carbon shell is graphitic and highly ordered due to the catalytic effects of the iron nanoparticles, which affect the electromagnetic properties of the composites. The electromagnetic wave absorption properties of the Fe@C composite and iron are estimated in the frequency range of 2.0-18.0 GHz, and as expected, the hierarchical rose-like porous Fe@C demonstrates outstanding reflection loss characteristics with a minimum value of -71.47 dB with a thin matched thickness of 1.48 mm. Moreover, an ultra-wide response bandwidth (reflection loss of less than -10 dB) of 2.88-18.0 GHz is achieved. Analysis of the electromagnetic properties revealed that the hierarchical rose-like Fe@C presents very different electromagnetic functions in comparison to pure iron and Fe@C particles without the rose-like structure derived from the iron alkoxide precursor with the same structure. The carbon shells and special morphology with a certain microstructure can effectively regulate the complex permittivity and permeability to modify the impedance matching characteristic as well as enhance the attenuation ability via electromagnetic wave multiple reflection and scattering in the hierarchical rose-like Fe@C particles. Analysis of the attenuation constant and matched characteristic impedance validates that the enhanced electromagnetic wave absorption of the rose-like Fe@C with a porous structure is due to the significant enhancement of matched impedance and collective multiple loss mechanism.