Ruilin Liu, Xiaomeng Jiang, Cui Ni, Baolei Wang, Chuanxin Hou, Xiaoyang Yang, Yuping Zhang, Wei Du, Xiubo Xie
Abstract Constructing a built‐in electric field (BIEF) is a proven strategy to enhance dielectric loss mechanisms by enhancing interfacial polarization. A multi‐shell pore‐filled heterostructured Co/Ni 3 ZnC 0.7 /C composite is synthesized through hydrogen plasma‐metal reaction, dealloying, vacuum filtration followed calcination. The Ni 3 ZnC 0.7 ratio to Co influence the electrical conductivity and graphitization degree. First‐principles calculations visualize the directional migration of space charges across the multi‐heterogeneous interfaces. The function difference spontaneously establishes a BIEF structure, significantly enhancing electromagnetic polarization loss and electromagnetic wave absorption (EMWA) capabilities. The C1.5NZC1 composite demonstrates exceptional performance, achieving a minimum reflection loss (RL min ) of −51.75 dB and an effective absorption bandwidth (EAB) of 5.64 GHz. Computational simulations reveal a maximum radar cross‐section (RCS) reduction of 35.2 dB·m 2 . The gradient multilayer structural design expands the EAB to 9.63 GHz, and its excellent thermal insulation and low infrared visibility improve practical applicability. This multi‐shell structure design with Ni 3 ZnC 0.7 loading in the pore and surface provides insights into designing heterointerfaces BIEF broadband EMW absorbers containing carbides.