MOF-derived yolk–shell Ni/C architectures assembled with Ni@C core–shell nanoparticles for lightweight microwave absorbents
MOF-derived yolk–shell Ni/C architectures assembled with Ni@C core–shell nanoparticles for lightweight microwave absorbents
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DOI：
10.1039/d0ce01242d
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发表时间：
2020-10
期刊：
影响因子：
3.1
通讯作者：
Xiaolei Wang;Q. Geng;G. Shi;Yajing Zhang;Da Li
中科院分区：
文献类型：
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作者：
Xiaolei Wang;Q. Geng;G. Shi;Yajing Zhang;Da Li
通过在500 °C和600 °C下分解镍基金属有机骨架（Ni-MOF），成功制备了由Ni@C核壳纳米粒子组成的卵黄壳型Ni/C微球。在PVP存在下，通过溶剂热法制备了具有蛋黄-壳结构的Ni-MOF，Ni（NO3）2. 6 H2O与C9 H6 O 6的摩尔比为1：1。提高热解温度可以提高Ni和C的结晶度，从而提高Ni/C微球的复介电常数，优化其微波阻尼阻抗匹配。随着热解温度的升高，Ni/C微球的衰减系数增大。在600 °C下得到的蛋黄壳状Ni/C微球具有最佳的反射损耗（RL），达到−39 dB，带宽为3.8 GHz（RL < −10 dB），集成带宽可达12.3 GHz，覆盖Ku波段（12-18千兆赫），X波段（8-12 GHz）和C波段的大部分（5.7-8 GHz），厚度为1.4-3.9 mm为宜。这种优异的微波吸收性能可归因于Ni/C微球由于自然共振而产生的磁损耗和介电损耗的协同效应，偶极极化和多个界面极化在一个独特的蛋黄-壳界面，实现阻抗匹配和微波衰减的优化。本工作表明，具有理想蛋黄-壳结构的Ni/C微球是微波吸收领域的潜在候选者。
Yolk–shell Ni/C microspheres composed of Ni@C core–shell nanoparticles were successfully fabricated by decomposing a Ni-based metal–organic framework (Ni-MOF) at 500 °C and 600 °C. The Ni-MOF with a yolk–shell structure was prepared by a solvothermal method with an appropriate molar ratio of Ni(NO3)2·6H2O to C9H6O6 in the presence of PVP. The degree of crystallization of Ni and C was improved by increasing the pyrolysis temperature, which resulted in enhanced complex permittivity and optimized impedance matching of Ni/C microspheres for damping microwave. Meanwhile, the attenuation coefficient of Ni/C microspheres increased with the increment in pyrolysis temperature. The yolk–shell Ni/C microspheres obtained at 600 °C exhibited the optimal reflection loss (RL) reaching −39 dB with a bandwidth of 3.8 GHz (RL < −10 dB) at a thin matching thickness of 1.8 mm. The integrated bandwidth can achieve 12.3 GHz covering Ku-band (12–18 GHz), X-band (8–12 GHz), and most of C-band (5.7–8 GHz) with an appropriate thickness of 1.4–3.9 mm. Such excellent microwave absorption performance can be attributed to the synergistic effect of the magnetic and dielectric losses of Ni/C microspheres due to natural resonance, dipolar polarization and multiple interfacial polarizations at a unique yolk–shell interface, achieving the optimization of impedance matching and microwave attenuation. This work demonstrates that Ni/C microspheres with a desirable yolk–shell structure are potential candidates for the application in microwave absorption field.