Rapid synthesis of nanoscale CoFe alloy anchored on carbon matrix via thermal shock for highly efficient electromagnetic wave absorption

Prussian blue analogue (PBA) derivatives have been widely regarded as next-generation electromagnetic (EM) wave absorbers, attributed to their tailorable architectures and compositions. However, conventional pyrolysis of PBA often causes agglomeration of metal nanoparticles and the destruction of polarization interfaces, thereby limiting EM dissipation capacity. To address this, we propose an ultrafast thermal shock strategy to synthesize nanoscale CoFe alloy anchored on a porous carbon matrix, utilizing CoFe-PBA as the precursor. The transient thermal shock process suppresses grain overgrowth while preserving structural defects, thereby generating abundant interfacial polarization sites and optimizing electrical conductivity. The resulting CoFe/C composite features rich interfacial structures and efficient charge transport pathways. Consequently, it delivers exceptional EM wave absorption performance with a minimum reflection loss of −43.24 dB at a thickness of 1.9 mm, alongside a broad effective absorption bandwidth of 5.57 GHz at 2.2 mm. Comprehensive electromagnetic analysis reveals that the superior performance originates from a synergistic mechanism involving a magnetic coupling network, enhanced interfacial and dipole polarizations, tailored conduction loss, and optimal impedance matching. This work not only presents a highly efficient EM wave absorber but also paves an efficient pathway for the rational design of advanced multi-component functional composites.