Guo Siyu, Cai Yanzhi, Cheng Laifei, Yuan Yibing, Wang Yuhan, Yu Haiming, Hu Zhongyi, Chen Dengpeng, Yuan Hudie
College of Materials Science and Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, Shaanxi, P. R. China.
Science and Technology on Thermostructure Composite Materials Laboratory, Northwestern Polytechnical University, Xi'an 710072, Shaanxi, P. R. China.
ACS Appl Mater Interfaces. 2024 Jun 26;16(25):32713-32726. doi: 10.1021/acsami.4c05050. Epub 2024 Jun 11.
Metal-organic frameworks (MOFs) have attracted attention due to their designable structures. However, recently reported MOF microwave-absorbing materials (MAMs) are dominated by powders. It remains a challenge to design MOF/carbon nanotube (CNT) composite structures that combine the mechanical properties of self-supporting flexibility with excellent microwave absorption. This work involves the hydrothermal approach to grow Ni-MOF of different microstructures in situ on the CNT monofilament by adjusting the molar ratio of nickel ions to organic ligands. Subsequently, an ultraflexible self-supporting Ni-MOF/CNT buckypaper (BP) is obtained by directional gas pressure filtration technology. The BP porous skeleton and the Ni-MOF with a unique porous structure provide effective impedance matching. The CNTs contribute to the conduction loss, the cross-scale heterogeneous interface generated by Ni-MOF/CNT BP provides rich interfacial polarization loss, and the porous structure complicates the microwave propagation path. All factors work together to give Ni-MOF/CNT BP an excellent microwave absorption capacity. The minimum reflection losses of Ni-MOF/CNT BPs decorated with granular-, hollow porous prism-, and porous prism-shaped Ni-MOFs reach -50.8, -57.8, and -43.3 dB, respectively. The corresponding effective absorption bandwidths are 4.5, 6.3, and 4.8 GHz, respectively. Furthermore, BPs show remarkable flexibility as they can be wound hundreds of times around a glass rod with a diameter of 4 mm without structural damage. This work presents a new concept for creating ultraflexible self-supported MOF-based MAMs with hierarchical interpenetrating porous structures, with potential application advantages in the field of flexible electronics.
金属有机框架材料（MOFs）因其可设计的结构而备受关注。然而，最近报道的MOF微波吸收材料（MAMs）主要是粉末状。设计兼具自支撑柔韧性的机械性能和优异微波吸收性能的MOF/碳纳米管（CNT）复合结构仍然是一个挑战。这项工作涉及通过调节镍离子与有机配体的摩尔比，采用水热法在CNT单丝上原位生长不同微观结构的Ni-MOF。随后，通过定向气压过滤技术获得了超柔性自支撑的Ni-MOF/CNT巴基纸（BP）。BP多孔骨架和具有独特多孔结构的Ni-MOF提供了有效的阻抗匹配。CNT有助于传导损耗，Ni-MOF/CNT BP产生的跨尺度异质界面提供了丰富的界面极化损耗，并且多孔结构使微波传播路径复杂化。所有这些因素共同作用，赋予Ni-MOF/CNT BP优异的微波吸收能力。用颗粒状、中空多孔棱柱形和多孔棱柱形Ni-MOF修饰的Ni-MOF/CNT BP的最小反射损耗分别达到-50.8、-57.8和-43.3 dB。相应的有效吸收带宽分别为4.5、6.3和4.8 GHz。此外，BP表现出显著的柔韧性，因为它们可以在直径为4 mm的玻璃棒上缠绕数百次而不发生结构损坏。这项工作提出了一种创建具有分级互穿多孔结构的超柔性自支撑MOF基MAMs的新概念，在柔性电子领域具有潜在的应用优势。
