Fe-Doped ZIF-67 Derived Carbon@polypyrrole Composites for Enhanced Electromagnetic Wave Absorption

The proliferation of electronic devices and wireless communication systems has intensified electromagnetic interference, creating a strong demand for high-performance electromagnetic wave (EMW) absorbers for electromagnetic compatibility and stealth-related applications. However, many existing synthesis routes rely on corrosive reagents, harsh conditions, or high energy input. Here, we report a relatively mild route to Fe-doped ZIF-67-derived carbon@polypyrrole (PPy) composites that combines potassium ferric oxalate-mediated etching, carbonization, and aqueous-phase polymerization. This etching step simultaneously introduces Fe species and generates defect-rich architectures and heterogeneous interfaces while largely retaining the porous framework, thereby enabling effective dielectric regulation. The heated–etched hf-CoFe/C@PPy composite delivers a minimum reflection loss of –65.77 dB and an effective absorption bandwidth of 6.06 GHz. Moreover, the room-temperature-etched hp-CoFe/C@PPy achieves a broad effective absorption bandwidth of 6.48 GHz at a thickness of 2.29 mm. Mechanistic analysis indicates that the superior performance arises from the synergistic effects of impedance matching, conductive loss, interfacial/dipolar polarization, multiple scattering, and quarter-wavelength cancellation. These results provide a viable route for designing high-performance EMW absorbers through a comparatively mild and environmentally more compatible process.