1成果简介

　　电磁波吸收材料在实际应用中不可避免地会遇到腐蚀性环境，因此抗腐蚀设计对于其实际部署至关重要。本文，西北工业大学孔杰 教授、邢瑞哲 副教授在《Journal of Materials Science & Technology》期刊发表名为“Magnetic graphene composite aerogel for highly efficient electromagnetic wave absorption and anti-corrosion”的论文，研究通过PHNiC与氧化石墨烯的自组装，随后进行化学还原和冻干处理，制备了磁性石墨烯复合气凝胶（还原氧化石墨烯（rGO）/多孔空心镍/碳微球（PHNiC））。
　　rGO/PHNiC气凝胶展现出优异的阻抗匹配和电磁衰减性能，在2.5 mm厚度下实现最低反射损耗为−51.3 dB，并具备6.64 GHz的宽有效吸收带宽。此外，通过界面钝化作用，rGO对磁性纳米颗粒的包覆形成防腐蚀屏障，有效抑制电解质渗透和阳极溶解。因此，rGO/PHNiC气凝胶展现出显著提升的抗腐蚀性能，其腐蚀电位为−0.45V（相对于饱和甘汞电极），腐蚀电流密度为3.3 μA，与未涂覆的对照组相比，腐蚀速率降低超过90%。本研究为在复杂环境中工作的微波吸收材料设计提供了宝贵启示。
　　2图文导读

　　图1. Schematic illustration for the preparation of rGO/PHNiC composite aerogel. Step I: Hydrothermal synthesis of Ni-MOF from NiSO₄·6H₂O and benzene-1,3,5-tricarboxylic acid, followed by pyrolysis to yield PHNiC. Step II: PHNiC and GO dispersion were mixed, reduced, and freeze-dried to form rGO/PHNiC aerogel.

　　图2. Morphology of rGO/PHNiC composite aerogels. SEM images of (a) PHNiC, (b) GA, and (c) and (d) rGO/PHNiC. (e) TEM and (f–i) HRTEM images of rGO/PHNiC. (j–m) TEM image and the corresponding elemental mapping of rGO/PHNiC-800, respectively.

　　图3. Structural characterizations of rGO/PHNiC composite aerogel: (a) XRD patterns. (b) Raman spectrum. (c) magnetic hysteresis loops. The inset figure is the enlarged coercivity of the samples. (d) XPS full spectrum and corresponding high-resolution XPS survey for rGO/PHNiC-800: (e) C 1s and (f) Ni 2p.

　　图4. Electromagnetic wave absorption performance of rGO/PHNiC composite aerogels. 3D RL diagram of (a) rGO/PHNiC-600, (b) rGO/PHNiC-700, and (c) rGO/PHNiC-800. 2D mapping of RL across frequency and thickness domains of (d) rGO/PHNiC-600, (e) rGO/PHNiC-700, and (f) rGO/PHNiC-800. (g) EAB for the aerogels. (h) RLmin values of the aerogels at different frequency bands. (i) Comparison of RLmin and EAB with previous works.

　　图5. Electromagnetic parameters of rGO/PHNiC composite aerogels. (a) Real part of permittivity, (b) imaginary part of permittivity, and (c) permeability. Electromagnetic parameters of (d) 20-rGO/PHNiC and (e) 30-rGO/PHNiC. (f) The loss tangent.

　　图6. Schematic diagram of the electromagnetic wave absorption mechanism of rGO/PHNiC. The electromagnetic wave dissipation mechanisms of rGO/PHNiC primarily include: dielectric/magnetic/conduction loss, carrier migration-induced conduction in graphene layers, dipole/interface polarization, and magnetic resonance mechanisms.

　　图7. Anti‑corrosion performance of rGO/PHNiC composite aerogels. (a) The OCP values 3.5 wt.% NaCl solution. (b) The Tafel curves. (c) The Nyquist plots, (d) phase angle plots, and (e) Bode plots of samples. (f) The equivalent circuit of corrosion.
　　3小结 
　　综上所述，通过一种简单的混合组装策略制备了磁性石墨烯复合气凝胶。在凝胶化过程中，rGO与PHNiC之间发生了协同共组装，且在组装过程中石墨烯片层被涂覆在PHNiC表面。通过引入PHNiC的磁损耗并优化阻抗匹配，rGO/PHNiC复合材料实现了卓越的电磁波吸收性能，包括在2.5 mm厚度和6.72 GHz有效带宽下达到的RLmin值为−51.3 dB。通过CST模拟进一步验证了显著的雷达截面积（RCS）降低效果。此外，合成的气凝胶还展现出优异的抗腐蚀能力；rGO/PHNiC的|Z|0.1 Hz值比PHNiC高2.04–2.26倍。本研究为设计兼具高性能电磁波吸收能力和良好抗腐蚀性能的材料提供了新思路。
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