Zhao Biao, Li Ruosong, Men Qiaoqiao, Yan Zhikai, Lv Hualiang, Wu Le, Che Renchao
School of Microelectronics, Fudan University, Shanghai, 200433, China.
School of Chemical Engineering, Northwest University, Xi'an, Shaanxi, 710069, China.
Small. 2024 Jan;20(3):e2208135. doi: 10.1002/smll.202208135. Epub 2023 Aug 16.
High-efficiency electromagnetic (EM) wave (EMW)-absorbing materials have attracted extensive scientific and technical interest. Although identifying the dominant EM loss mechanism in dielectric-loss materials is indispensable, it is challenging due to a complex synergism between dipole/interfacial polarization and conduction loss. Modulation of defects and microstructures can be a possible approach to determine the dominant EM loss mechanism and realize high-efficiency absorption. Herein, 2D reduced graphene oxide (rGO) flakes are integrated into a 3D hollow bowl-like structure, which increases defect sites (i.e., oxygen vacancy and lattice defect) and reduces the stacked thickness of rGO. Despite their lower stacked thicknesses, the hollow rGO bowls with more defects exhibit lower conductivities but higher permittivities. Accompanied by the transformation from 2D flakes to 3D hollow bowls, the dominant EM loss mechanism of rGO transforms from conduction loss to defect-induced polarization. Furthermore, the defect engineering and structural design endow rGO with well-matched impedance and strong EMW-absorbing capacity. A minimum reflection loss of -41.6 dB (1.3 mm) and an effective absorption bandwidth of 4.8 GHz (1.5 mm) is achieved at a filler loading of 5 wt%. This study will provide meaningful insights into the development of materials with superior EMW-absorbing performances via defect engineering and structural design.
高效电磁波吸收材料已引起广泛的科学技术关注。尽管确定介电损耗材料中的主要电磁损耗机制必不可少，但由于偶极/界面极化与传导损耗之间存在复杂的协同作用，这一过程具有挑战性。调制缺陷和微观结构可能是确定主要电磁损耗机制并实现高效吸收的一种方法。在此，二维还原氧化石墨烯（rGO）薄片被整合到三维中空碗状结构中，这增加了缺陷位点（即氧空位和晶格缺陷）并减小了rGO的堆叠厚度。尽管其堆叠厚度较小，但具有更多缺陷的中空rGO碗表现出较低的电导率但较高的介电常数。伴随着从二维薄片到三维中空碗的转变，rGO的主要电磁损耗机制从传导损耗转变为缺陷诱导极化。此外，缺陷工程和结构设计赋予rGO良好匹配的阻抗和强大的电磁波吸收能力。在填料含量为5 wt%时，实现了-41.6 dB（1.3 mm）的最小反射损耗和4.8 GHz（1.5 mm）的有效吸收带宽。本研究将为通过缺陷工程和结构设计开发具有优异电磁波吸收性能的材料提供有意义的见解。
