Fish Tofu-structured Se/prussian blue derived composites for exceptional microwave absorption

The strategic design of eco-friendly prussian blue (PB) materials is essential for their effective application in both microwave absorption (MA) and organic dye adsorption. In this study, a one-pot selenization heat treatment method is utilized to synthesize Se-coated Co-PB (Se/PB) composites with a distinctive “fish tofu” structure. The incorporation of selenium promotes the formation of CoSe₂ on the surface of Co-PB, which in turn catalyzes the pyrolysis of Co-PB, resulting in the formation of small-sized C-CoSe₂ nanoparticles. This distinctive “fish tofu” morphology plays a crucial role in enhancing the multiple reflections and scattering of electromagnetic waves (EMW). Additionally, the dipole polarization and interfacial effects, induced by the internal defects in C-CoSe₂ during the selenization process, further improve impedance matching. Among the composites, Se/PB-600 demonstrates a minimum reflection loss (RL_min) of −70.56 dB, while Se/PB-300 achieves a maximum effective absorption bandwidth (EAB_max) of 6.72 GHz, representing a 630.11 % enhancement in RL_min compared to pristine Co-PB. Furthermore, the porous structure of the “fish tofu” morphology significantly improves methylene blue adsorption, reaching equilibrium within 600 min and attaining a maximum adsorption capacity of 39.85 mg/g. This dual-functional approach not only broadens the potential applications of PB in MA but also provides valuable insights into the design of high-performance bifunctional microwave absorption materials.