Polypyrrole in-situ encapsulated Prussian blue analogues with diverse topologies for high-efficiency electromagnetic wave absorption

The poor conductivity of Prussian Blue Analogues (PBAs) and their tendency to agglomerate during pyrolysis limit their application in the field of microwave absorption. To address the aforementioned issues, this study employed polypyrrole (PPy) as a coating layer and utilized Prussian blue analogues (PBAs) with uniform particle sizes in box-like and cage-like topological structures as precursors, successfully preparing B-CoFe/C@PPy and C-CoFe/C@PPy nanoparticles featuring heterogeneous interfaces. The method utilizes a post-thermal-treatment ice-bath coating process, which effectively preserves the original morphological structure of nanoparticles while achieving successful PPy encapsulation. The PPy coating significantly enhances the material's dielectric constant, thereby improving impedance matching and conductive loss. And combined with the synergistic effect of interfacial polarization relaxation induced by heterogeneous interfaces, the composite achieves exceptional EMWA performance. At a filler loading of 30 wt%, C-CoFe/C@PPy exhibits an effective absorption bandwidth of 6.16 GHz at a thickness of 2.2 mm, and the minimum reflection loss can reach −28.10 dB at 1.8 mm. It is believed that this work will enrich the research on polymer-encapsulated PBAs-derived microwave absorbing materials with superior performance.