Prussian blue–derived CoNi bimetallic decoration of SiOC ceramics with enhanced dielectric attenuation for broadband microwave absorption

Prussian blue offers compositional precision for constructing transition‑metal nanostructures; however, their integration into polymer‑derived ceramics (PDCs) for high‑frequency electromagnetic (EM) attenuation remains underexplored. Herein, a Prussian blue‑derived CoNi coordination framework is incorporated into a polysiloxane (PSO) precursor and converted into CoNi–SiOC ceramic via pressureless sintering. With increasing heat-treatment temperature, the CoNi gradually decomposed. Co catalyzed the formation of carbon nanowires (CNWs), while Ni species reacted with the SiOC matrix to form Ni₂Si and generate Co_xNi_1-x, SiC, and SiO₂, which were precipitated from the ceramic matrix, leading to the construction of a multiphase, multiscale heterogeneous interfacial architecture. Notably, the CoNi–SiOC ceramic (CNS-3) treated at 1100 °C showed outstanding EM wave attenuation capability. A minimum reflection loss of − 50.3 dB was obtained at a thickness of 2.35 mm, while an effective absorption bandwidth of 5.6 GHz was achieved when the thickness ranged from 2.35 to 2.45 mm, completely spanning the Ku band. In addition, radar cross-section (RCS) simulations based on CST revealed a reduction of up to 17.25 dB m², highlighting the strong potential of CoNi–SiOC ceramics for EM stealth applications.