Three−dimensional (3D) hierarchical nano−microstructures have shown unprecedented physicochemical properties. However, it still remains great challenge to construct well−defined architectures with 3D hierarchical feature. Herein, we develop an electrospinning technique followed by a high−temperature carbonization process to fabricate N−doped carbon fibers (NCF) with N−doped carbon nanotubes (NCNTs) vertically grown on the surface of NCF using the Fe species as catalysts. In the 3D hierarchical structures, the Fe₃C nanoparticles (NPs) are embedded within NCF matrix, while the Fe NPs are encapsulated within NCNT. Due to the unique structural feature, the as−prepared hierarchical structure exhibits excellent electromagnetic wave absorption performance with an absorption bandwidth of 4.0 GHz and a minimum reflection loss of −49.56 dB with a thickness as low as 1.50 mm. Experimental and theoretical studies indicate that the enhanced electromagnetic wave absorption performance of the hierarchical structure can be explained by the increased conduction loss induced by the introduction of metallic NPs and formation of 3D conductive networks, and the enhanced polarization loss caused by the additional interfaces and defects in the hierarchical structure. This work provides an efficient way to fabricate 3D architecture for high−efficiency electromagnetic wave absorption.

三维 (3D) 分层纳米微结构已显示出前所未有的物理化学特性。然而，构建具有 3D 分层特征的定义明确的架构仍然是巨大的挑战。在此，我们开发了一种静电纺丝技术，然后采用高温碳化工艺制造 N 掺杂碳纤维（NCF），其中 N 掺杂碳纳米管（NCNT）使用 Fe 物质作为催化剂垂直生长在 NCF 表面上。在 3D 层次结构中，Fe ₃C 纳米颗粒 (NPs) 嵌入 NCF 基质中，而 Fe NPs 封装在 NCNT 中。由于独特的结构特征，所制备的分层结构表现出优异的电磁波吸收性能，吸收带宽为4.0 GHz，最小反射损耗为-49.56 dB，厚度低至1.50 mm。实验和理论研究表明，分层结构增强的电磁波吸收性能可以解释为金属纳米粒子的引入和 3D 导电网络的形成导致的传导损耗增加，以及额外的界面和缺陷导致的极化损耗增加。在层次结构中。