Structuring Hierarchically Porous Architecture in Biomass-Derived Carbon Aerogels for Simultaneously Achieving High Electromagnetic Interference Shielding Effectiveness and High Absorption Coefficient
Structuring Hierarchically Porous Architecture in Biomass-Derived Carbon Aerogels for Simultaneously Achieving High Electromagnetic Interference Shielding Effectiveness and High Absorption Coefficient
复制标题
在生物质衍生碳气凝胶中构建分级多孔结构，同时实现高电磁干扰屏蔽效能和高吸收系数
DOI：
10.1021/acsami.0c01190
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发表时间：
2020-04-22
影响因子：
9.5
通讯作者：
Li, Zhong-Ming
中科院分区：
文献类型：
--
作者：
Zhou, Zi-Han;Li, Meng-Zhu;Li, Zhong-Ming
为消除反射电磁波的二次污染，研制高性能的高吸收系数电磁干扰屏蔽材料是十分必要的。然而，长期以来，同时实现高屏蔽效能（SE）和超低或无反射SE一直是一个艰巨的挑战。在此，通过特定的两阶段热解和氢氧化钾活化过程开发了具有从微米和亚微米到纳米级精心设计的分级多孔结构的高度多孔和导电的碳纳米管（CNT）基碳气凝胶。所得的活化纤维素衍生的碳气凝胶（a-CCA）在8.2- 12.4GHz的频率范围内表现出96.4dB的EMI SE以及在30.5mg cm（-3）的低密度下0.79的异常高的吸收系数。多层多孔结构的成功构建是a-CCAs优异的“结构吸收”能力的主要原因，而碳纳米管基异质导电网络的引入可以通过界面极化和微电流损耗有效地耗散入射电磁波。此外，所制备的a-CCAs具有高达158.3度的水接触角和低至5.3度的滑动角，显示其超疏水特性。这种新颖的结构设计为解决高电磁屏蔽性能与超低或无二次反射之间的矛盾提供了一条可能的途径，在通信、微电子和航天器等领域具有广阔的应用前景。
Developing high-performance electromagnetic interference (EMI) shielding materials with high absorption coefficient is highly desired for eliminating the secondary pollution of reflected electromagnetic wave (EMW). Nevertheless, it has long been a daunting challenge to achieve high shielding effectiveness (SE) and ultralow or no reflection SE simultaneously. Herein, highly porous and conductive carbon nanotube (CNT)-based carbon aerogel with a meticulously designed hierarchically porous structure from micro and sub-micro to nano levels is developed by specific two-stage pyrolysis and potassium hydroxide activation processes. The resultant activated cellulose-derived carbon aerogels (a-CCAs) exhibit an ultrahigh EMI SE of 96.4 dB in the frequency range of 8.2-12.4 GHz in conjunction with an exceptionally high absorption coefficient of 0.79 at a low density of 30.5 mg cm(-3). The successful construction of hierarchically porous structure is responsible for the excellent "structurally absorbing" ability of a-CCAs, and the introduction of CNT-based heterogeneous conductive network can effectively dissipate the incident EMWs by interfacial polarization and microcurrent losses. Moreover, the as-prepared a-CCAs have a water contact angle of as high as 158.3 degrees and a sliding angle of as low as 5.3 degrees, revealing their superhydrophobic feature. The ingenious structure design proposed here provides a possible pathway to overcome the conflict between high EMI shielding performance and ultralow or no secondary reflection, and the as-prepared a-CCAs are exceedingly promising in the application of telecommunication, microelectronics, and spacecraft.