Pomb@Co3O4-based composites for ultra-wideband microwave absorption: A multi-scale perspective from micro-, meso- and meta-structure

Abstract

Microwave absorbing materials (MAMs) are used to prevent electromagnetic pollution and enhance equipment stealth. However, their limited absorption intensity and narrow effective bandwidth restrict their applicability. MAMs with a single absorption mechanism, whether dielectric or magnetic, often exhibit poor impedance matching. This paper introduces a new multiscale approach—encompassing microstructures, mesostructures and macrostructures—for designing high-performance MAMs. At the microscopic–mesoscopic level, Pomb materials derived from pomegranate peel are combined with magnetic nanoparticles (Co3O4) using a hydrothermal method. The microwave absorption properties of these composite materials were examined by varying the proportion of Pomb materials in the absorber. The effective absorption bandwidth (EAB) reached 5.5 GHz for a thickness of 2.3 mm. At the macroscopic level, a metastructure based on Pomb@Co3O4 (0.1 g) was designed to achieve ultrabroadband absorption with an EAB of 15.56 GHz, a range of 2.24–18 GHz and a total thickness of 15 mm. Additionally, the radar cross-section value of Pomb@Co3O4 (0.1 g) is below − 10 dB m2 across the angle range of − 60° to 60°, with a maximum scattering intensity of only − 7.6 dB m2. This multiscale structure design offers a promising direction for future research and development in MAMs.