Microporous Co@CoO nanoparticles with superior microwave absorption properties
Microporous Co@CoO nanoparticles with superior microwave absorption properties
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DOI：
10.1039/c3nr05238a
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发表时间：
2014-01-01
期刊：
影响因子：
6.7
通讯作者：
Kobayashi, Satoru
中科院分区：
文献类型：
--
作者：
Liu, Tong;Pang, Yu;Kobayashi, Satoru
化学脱合金法是一种制备纳米多孔金属材料的新方法。然而，由于难以制备合适的纳米级前体，纳米多孔金属纳米颗粒（NPs）的制备仍然具有挑战性。本文中，通过使Co-Al NP脱合金化，已经成功地制备了31 nm的纳米多孔Co NP，并且令人惊讶地，它们具有0.7至1.7 nm范围内的微孔和50 m2/g的大表面积。微孔NP的晶体尺寸为2-5 nm。通过钝化处理，Co表面氧化生成了表面覆盖有CoO（Co@CoO）的微孔Co纳米粒子，其微波吸收性能优于无孔纳米粒子。对于厚度仅为1.3 mm的微孔Co@CoO NPs，获得了-90.2 dB的增强反射损耗（RL）值。对应于RL低于-10 dB的吸收带宽达到7.2 GHz。从纳米粒子的形貌、核壳结构和纳米结构三个方面讨论了其吸波机理。这种新型微孔材料为设计高性能微波吸收剂开辟了新的途径。
Nanoporous metal materials with many potential applications have been synthesized by a chemical dealloying approach. The fabrication of nanoporous metal nanoparticles (NPs), however, is still challenging due to the difficulties in producing suitable nanoscale precursors. Herein, nanoporous Co NPs of 31 nm have been successfully prepared by dealloying Co-Al NPs, and surprisingly they possess micropores in a range from 0.7 to 1.7 nm and a large surface area of 50 m(2) g(-1). The crystalline size of the microporous NPs is 2-5 nm. Through the passivation process, the microporous Co NPs covered with CoO (Co@CoO) are generated as a result of the surface oxidation of Co. They exhibit better microwave absorption properties than their nonporous counterpart. An enhanced reflection loss (RL) value of -90.2 dB is obtained for the microporous Co@CoO NPs with a thickness of merely 1.3 mm. The absorption bandwidth corresponding to the RL below -10 dB reaches 7.2 GHz. The microwave absorption mechanism is discussed in terms of micropore morphology, core@shell structure and nanostructure. This novel microporous material may open new routes for designing high performance microwave absorbers.