High-Entropy (MnCoNiFeCu)-O@PPy Nanocomposites with Enhanced Corrosion Resistance for Microwave Absorption and Loss Control

In this study, the microwave absorption of the high-entropy oxide nanocomposite (Mn 0.2 Co 0.2 Ni 0.2 Fe 0.2 Cu 0.2 ) 3 O 4 @PPy with a content of 40 wt % mixed in paraffin wax achieved a minimum reflection loss (RL) value of −60.76 dB and an effective absorption bandwidth (RL < −10 dB) of 6.9 GHz at a corresponding thickness of 2.15 mm. This indicates that the nanocomposite’s microwave absorption rate can exceed 99%, featuring a wider absorption bandwidth and a smaller thickness, making it an excellent wave-absorbing material. The superior impedance matching, larger attenuation coefficient, and dielectric-magnetic loss coupling effect of the wave absorber, along with the presence of multiple polarization phenomena within the material, collectively enhance the wave absorption effect. By the CST electromagnetic simulation, it was found that the simulation fitting of ε and μ closely matches the experimental results. This demonstrates that the nanocomposites possess strong microwave-absorbing capabilities, making them viable as new and efficient absorber materials. In addition, we evaluated the corrosion protection properties of the material, and the results demonstrated that it possesses significant corrosion resistance. This study confirms that (Mn 0.2 Co 0.2 Ni 0.2 Fe 0.2 Cu 0.2 ) 3 O 4 @PPy can serve as a multifunctional nanocomposite material effective for both wave absorption and corrosion resistance across various applications and fields.