Ultralight Cellular Foam from Cellulose Nanofiber/Carbon Nanotube Self-Assemblies for Ultrabroad-Band Microwave Absorption.
Ultralight Cellular Foam from Cellulose Nanofiber/Carbon Nanotube Self-Assemblies for Ultrabroad-Band Microwave Absorption.
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DOI：
10.1021/acsami.9b03731
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发表时间：
2019-06
影响因子：
9.5
通讯作者：
Hailong Xu;X. Yin;Minghang Li;Xinliang Li;Xin Li;Xiaolin Dang;Litong Zhang;Lai-fei Cheng
中科院分区：
文献类型：
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作者：
Hailong Xu;X. Yin;Minghang Li;Xinliang Li;Xin Li;Xiaolin Dang;Litong Zhang;Lai-fei Cheng
在先进的吸波材料中，迫切需要具有轻质密度和超宽带吸波性能的吸波材料，这仍然是一个很大的挑战，并且很少实现。本文设计了一种新的宽带吸收模型，该模型融合了周期性多孔结构在低频范围内的电磁谐振损耗能力和介质材料在高频范围内的介电损耗能力。在此基础上，以碳纳米管（CNT）和纤维素纳米管（CNF）为“积木”，采用冰模板法制备了一种轻质多孔CNF/CNT泡沫材料，该泡沫材料由大孔直径为30 ~ 90 μm的蜂窝状垂直孔结构和1.7 ~ 50 nm的纳米孔结构组成。得益于独特的结构，其有效吸收带宽达到29.7 GHz，比吸波性能超过80，000 dB·cm-2·g-1，远远超过此前报道的MAMs，包括所有CNT基复合材料。此外，CNF/CNT泡沫具有超低的密度（9.2 mg/cm 3）和强的抗疲劳性，所有这些都来自于良好的互连的多孔结构和CNF-CNF和CNF-CNT分子链之间的强氢键。
Microwave absorption materials (MAMs) with lightweight density and ultrabroad-band microwave absorption performance are urgently needed in advanced MAMs, which are still a big challenge and have been rarely achieved. Here, a new wide bandwidth absorption model was designed, which fuses the electromagnetic resonance loss ability of a periodic porous structure in the low-frequency range and the dielectric loss ability of dielectric materials in the high-frequency range. Based on this model, a lightweight porous cellulose nanofiber (CNF)/carbon nanotube (CNT) foam consisting of a cellular vertical porous architecture with the macropore diameters between 30 and 90 μm and a nanoporous architecture at a scale of 1.7-50 nm was obtained by an ice-template method using CNTs and CNFs as "building blocks". Benefiting from the unique architecture, the effective absorption bandwidth reaches 29.7 GHz, and its specific microwave absorption performance exceeds 80,000 dB·cm-2·g-1, which far surpasses those of the MAMs previously reported, including all CNT-based composites. Moreover, the CNF/CNT foam possesses ultralow density (9.2 mg/cm3) and strong fatigue resistance, all coming from the well-interconnected porous structure and the strong hydrogen bonds among CNF-CNF and CNF-CNT molecular chains.