Novel core/shell Fe3O4/C/polypyrrole (PPy) composites were prepared via facile hydrothermal and chemical oxidative polymerization method. The obtained Fe3O4/C/PPy exhibits a dual core–shell structure in which an intermediate carbon layer provides excellent electrical connectivity between Fe3O4 nanoparticles and PPy polymer. Further, these trilaminar core/shell composites were investigated for EMI shielding material to prevent EMI pollution. The excellent EMI shielding efficiency (> 28) dB was attained for Fe3O4/C:PPy (2:8 wt/wt) at thickness 0.8 mm which is mainly governed by absorption. Additional evidence of superior EMI absorption performance is the magnetic property of Fe3O4/C:PPy composites. It was observed that magnetic properties of Fe3O4/C:PPy composites highly depend on the content and thickness of the shell which influences the spin motion of Fe3O4 nanoparticles. Thus, it is anticipated that spin motion plays a decisive role in EMI shielding performance of Fe3O4/C/PPy composites.

中文翻译：

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自旋无序在 Fe3O4/C/PPy 核/壳复合材料的磁性和 EMI 屏蔽性能中的作用

通过简便的水热和化学氧化聚合方法制备了新型核/壳 Fe3O4/C/聚吡咯 (PPy) 复合材料。获得的 Fe3O4/C/PPy 表现出双核壳结构，其中中间碳层在 Fe3O4 纳米颗粒和 PPy 聚合物之间提供了良好的电连接性。此外，研究了这些三层核/壳复合材料作为 EMI 屏蔽材料以防止 EMI 污染。Fe3O4/C:PPy (2:8 wt/wt) 在厚度为 0.8 mm 时获得了出色的 EMI 屏蔽效率 (> 28) dB，这主要取决于吸收。Fe3O4/C:PPy 复合材料的磁性是优异 EMI 吸收性能的其他证据。观察到 Fe3O4/C 的磁性：PPy 复合材料高度依赖于影响 Fe3O4 纳米粒子自旋运动的壳的含量和厚度。因此，预计自旋运动在 Fe3O4/C/PPy 复合材料的 EMI 屏蔽性能中起决定性作用。