Morphology control of CoMn/C composites via facet engineering in precursors toward superior electromagnetic wave absorption

The precise regulation of microstructures in electromagnetic wave absorption materials represents a pivotal strategy for achieving superior electromagnetic wave absorption performance. However, unclear microstructure absorption relationships hinder rational design of high performance absorbers. Herein, a crystal facet engineering strategy was developed to achieve precise morphological control of CoMn Prussian Blue Analogues (PBAs) without altering the intrinsic composition, enabling the synthesis of cross shaped (CS), spherical like (SL) and hexagonal (H) PBAs. The pyrolyzed CS CoMn/C composites retain the pristine topological framework while exhibiting a rich interfacial architecture and high specific surface area. Systematic experimental characterization combined with theoretical simulations reveals that the optimized microstructure significantly influences the distribution of polarization charges, which in turn governs the electromagnetic wave dissipation behavior. Consequently, at a thickness of 2.0 mm, the CS CoMn/C complex achieves an effective absorption bandwidth (EAB) of 5.81 GHz, covering 96.7% of the Ku band. Gram scale synthesis demonstrates the excellent stability of the proposed strategy. This work not only establishes a clear correlation between microstructural parameters and electromagnetic loss mechanisms but also provides a versatile, scalable and controllable approach for the rational design of high performance electromagnetic wave absorption materials.