Integration of Asymmetric Multi-Path Hollow Structure and Multiple Heterogeneous Interfaces in Fe₃O₄@C@NiO Nanoprisms Enabling Ultra-Low and Broadband Absorption

A reasonable construction of hollow structures to obtain high-performance absorbers is widely studied, but it is still a challenge to select suitable materials to improve the low-frequency attenuation performance. Here, the Fe₃O₄@C@NiO nanoprisms with unique tip shapes, asymmetric multi-path hollow cavity, and core–shell heteroepitaxy structure are designed and synthesized based on anisotropy and intrinsic physical characteristics. Impressively, by changing the load of NiO, the composites achieve strong absorption, broadband, low-frequency absorption: the reflection loss of −55.8 dB and the absorption bandwidth of 9.9 GHz covers both low and high frequency (2.9–6.1 and 11.3–18 GHz). The constructed anisotropic hollow and heterointerface nanoprisms can optimize impedance matching for low-frequency absorption (3.8–7.9 GHz) almost completely covering the 5G band. Especially, the influence of hollow path on the interface polarization and ferromagnetic coupling behavior is revealed through the simulation of electric and magnetic field distribution using the High-Frequency Structure Simulator (HFSS). In addition, HFSS simulation shows that the Radar Cross-Sectional (RCS) value of the absorber at any angle is <−10 dB m², which meets the complex requirements in practical application. This research paves a new way for the development of efficient low-frequency absorbers based on composition and structure design.