Integrating hierarchically ordered porous structures within the three-dimensional structural cavity framework of diatoms is expected to be a feasible approach for improving electromagnetic wave absorption performance. However, its internal mechanism has not been thoroughly studied. This study pioneers the integration of naturally derived diatom biochar as a 3D template with MOF-based electromagnetic absorbers (ZIF-67). Natural 3D resonant cavities of diatom and secondary pore channels of ZIF-67 collaboratively construct a dual-templating effect to realize impedance stepwise matching. During pyrolysis, the formed Co-C/SiO 2 heterointerfaces induce strong interfacial polarization, while cobalt nanoparticles embedded within conductive carbon shells constitute magneto-dielectric coupling units, enabling tunable electromagnetic wave absorption. The material achieves exceptional performance at 2.4 mm thickness: strong absorption (−58.90 dB) and broad effective absorption bandwidth (5.35 GHz). Far-field RCS simulations verify a radar cross-section reduction of 27.4 dB·m 2 , significantly reducing target detectability. Thus, by customizing the hierarchical pore structure of biological templates to develop lightweight microwave stealth materials, this work provides a green pathway for multi-band compatible stealth technology. This paper pioneers the utilization of Nitzschia palea - a species of diatomite - for microwave absorption applications. Capitalizing on its elegantly hollow microstructure, achieving ultra-strong absorption (RL min = −58.90 dB, EAB max = 5.35 GHz) at 2.4 mm; experimental-simulation synergy: Far-field RCS simulations verify a radar cross-section (RCS) reduction of 27.4 dB m 2 (φ = 0° and θ = 0°), demonstrating practical stealth utility.
Liu et al. (Sun,) studied this question.