Magnetic-dielectric synergy in CoFe2O4-decorated MnO2 nanowires for efficient electromagnetic wave absorption

Manganese dioxide (MnO 2 ) has attracted considerable interest in electromagnetic wave (EMW) absorption owing to its high dielectric loss capability and morphological diversity. However, its practical application is largely restricted by poor impedance mismatch and a single loss mechanism. In this work, a series of CoFe 2 O 4 /MnO 2 composites were constructed via a two-step hydrothermal method, wherein MnO 2 nanowires served as the dielectric scaffold and CoFe 2 O 4 nanoparticles were introduced as magnetic modifiers to modulate the electromagnetic parameters and optimize impedance matching. The optimized composite achieves a minimum reflection loss of −50.87 dB at a thickness of 2.5 mm and a maximum effective absorption bandwidth of 6.41 GHz. The enhanced absorption performance is primarily attributed to the strong conduction loss derived from the three-dimensional MnO 2 conductive network, the interfacial polarization induced by the abundant CoFe 2 O 4 /MnO 2 heterojunctions, and the dipolar polarization contributed by oxygen vacancies. This work demonstrates that rational incorporation of magnetic components into a MnO 2 matrix provides a promising strategy for the design and development of high-performance EMW absorbers.