Jin Haoshan, Zhou Jintang, Tao Jiaqi, Gu Yansong, Yu Chunyi, Chen Ping, Yao Zhengjun
Key Laboratory of Material Preparation and Protection for Harsh Environment, Ministry of Industry and Information Technology, College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing, Jiangsu, 211100, P. R. China.
Department of Chemistry, Xi'an Jiaotong-Liverpool University, Suzhou, Jiangsu, 215123, P. R. China.
Small. 2023 Nov;19(46):e2304536. doi: 10.1002/smll.202304536. Epub 2023 Jul 20.
Oxygen-containing functional groups have high potential to excite polarization loss. The nature and mechanism of the polarization loss brought on by oxygen-containing functional groups, however, remain unclear. In this study, metal-organic framework precursors are in situ pyrolyzed to produce ultrathin carbon nanosheets (UCS) that are abundant in oxygen functional groups. By altering the pyrolysis temperature, the type and concentration of functional groups are altered to produce good microwave absorption capabilities. It is demonstrated that the main processes of electromagnetic loss are polarization caused by "field effects and induced effects" brought on by strongly polar ester functional groups. Moreover, links between various oxygen functional groups and structural flaws are established, and their respective contributions to polarization are sharply separated. The sample with the highest ester group content ultimately achieves an effective absorption bandwidth of 6.47 GHz at a pyrolysis temperature of 800°C. This research fills a theoretical hole in the frequently overlooked polarization mechanism in the microwave band by defining the key polarization parameters in chaotic multiple dipole systems and, in particular, redefining the significance of ester groups.
含氧官能团极易引发极化损耗。然而，含氧官能团所导致的极化损耗的本质和机制仍不明确。在本研究中，金属有机框架前驱体被原位热解以制备富含氧官能团的超薄碳纳米片（UCS）。通过改变热解温度，官能团的类型和浓度得以改变，从而产生良好的微波吸收能力。结果表明，电磁损耗的主要过程是由强极性酯官能团引起的“场效应和感应效应”导致的极化。此外，还建立了各种氧官能团与结构缺陷之间的联系，并将它们对极化的各自贡献清晰地区分开来。酯基含量最高的样品最终在800℃的热解温度下实现了6.47 GHz的有效吸收带宽。本研究通过定义混沌多偶极子系统中的关键极化参数，特别是重新定义酯基的意义，填补了微波波段中经常被忽视的极化机制的理论空白。
