新型多孔石墨烯基复合材料的电磁调控机制与吸波机理研究

The purpose of this project is to fabricate hierarchical microwave absorption materials with wider bandwidth and stronger absorption performance. The polyaniline nanorods and ferrite nanowires will be covalently bonded to the surface of porous graphene, and then we will explore the regulatory mechanism of electromagnetic parameters for porous graphene as a result of covalent bond. This research will reveal the impact of microscopic morphology of porous graphene such as its pore distribution, pore diameter, pore density, state of aggregation and that of polyaniline nanorods and ferrite nanowires on the conductivity, electromagnetic parameters and microwave absorption properties of composite materials. More importantly, we can also systematically study how the way in which polyaniline nanorods and ferrite nanowires bond with porous graphene, the location where they are distributed as well as their load rate influence density distribution and degree of polarization of the electron cloud on the surface of porous graphene, which again influence the electromagnetic parameters and microwave absorption performance of the composite. Based on exploring ways and degree of polarization and transmittal mode of electrons and magnetic flux, it will further elaborate the electromagnetic regulation and microwave absorption mechanism of porous graphene-based composites. The project will show that the electromagnetic parameters and microwave absorption performance of three-dimensional porous graphene can be regulated by adjusting its micro-structure and bonding mode with other chemicals, which will provide the theoretical foundation for the design of new microwave absorption materials (thin, light, wide and strong).

本项目旨在研究一种吸收频带宽且吸收强度大的多级结构吸波材料，以共价键将聚苯胺纳米棒和铁氧体纳米线垂直分布在多孔石墨烯表面，探索共价键连接聚苯胺纳米棒和铁氧体纳米线对多孔石墨烯电磁参数的调控机制。不仅揭示多孔石墨烯的孔分布、孔径、孔密度、聚集状态、聚苯胺纳米棒和铁氧体纳米线等微观形貌对复合材料电导率、电磁参数、吸波性能的影响，而且将系统地研究聚苯胺纳米棒、铁氧体纳米线与多孔石墨烯的键合方式、分布位置及负载率对多孔石墨烯表面电子云密度分布和极化程度的影响，进而影响电磁参数和吸波性能。从极化方式、极化程度、电子和磁流子传递方式上，揭示多孔石墨烯基复合材料的电磁调控机制与吸波机理。通过本项目的研究，可从结构和键合方式上操控三维多孔石墨烯的电磁参数和吸波性能，为设计“薄、轻、宽、强”的新型吸波材料奠定理论基础。

电子、通讯设备的广泛使用使电磁波辐射污染日益严重，因此研究电磁波吸收材料有着迫切的实际需要，相对于传统的吸波材料而言，石墨烯独特的二维结构使其具有质量轻、比表面积大、电子迁移率高、环境稳定性好等特点，是一种潜在的吸波材料。但制备过程中石墨烯电导率较高，导致较弱的阻抗匹配，对吸波性能产生不可忽略的影响。本项目将石墨烯和改性石墨烯与其他类型吸波材料进行复合构筑了石墨烯基三维结构复合材料，并研究了其吸波机理。主要研究内容及成果有：（1）采用水热法和原位聚合法合成了以共价键连接的聚苯胺（PANI）/石墨烯气凝胶（GA）复合材料。通过各种表征手段，研究了PANI与GA之间的化学键合和微观形貌。结合阻抗匹配、协同作用、PANI和GA的分级结构，与GA相比，PANI/GA明显地改善了微波吸收性能。PANI/GA在11.2 GHz下的反射损耗（RL）为-42.3 dB，匹配厚度为3 mm，相应的吸收带宽（RL ≤10dB）为3.2 GHz（8.7-11.9 GHz）。一方面，PANI与GA之间的电子运输通道增加了电子极化，改善了阻抗匹配。另一方面，PANI/GA的阻抗匹配和协同效应的改善导致了电磁波的强吸收。鉴于PANI/GA具有优异的微波吸收性能，我们认为利用共价键将PANI纳米棒固定在GA上是获得高性能微波吸收剂的有效选择。（2）通过简单的水热-煅烧两步法在磁性石墨烯片层上生长ZnO纳米粒子，成功地设计了NiFe2O4/N-GN/ZnO三维复合材料。与NiFe2O4/N-GN复合材料相比，NiFe2O4/N-GN/ZnO复合材料具有更强的电磁波吸收性能。低填料负载为20 wt％时，在13.5 GHz时最强的反射损耗（RL）高达-70.7 dB，并且在2.7 mm厚度下的吸收剂的有效吸收带宽（RL≤−10 dB）达到3.5 GHz（11.7-15.2 GHz）。（3）通过简单的水热法成功地将空心ZnSnO3纳米晶体生长在氮掺杂石墨烯纳米片上（ZnSnO3-NRGO），合理的阻抗匹配、较高的衰减能力、适宜的协同效应和多重界面极化增强了吸波性能。