Polymorphic cerium-based Prussian blue derivatives with in situ growing CNT/Co heterojunctions for enhanced microwave absorption via polarization and magnetization

In this paper, the structure evolution of cerium cobaltohexanoate (Ce[Co(CN)₆], Ce-Co Prussian blue analog (PBA)) has been realized by solvent catalysis at room temperature. The hexagonal bipyramidal microcrystals of Ce-Co PBA can be gradually transformed into dendrites by different proportions of ethanol (EtOH) and water. At the same time, the porous dendrites CeO₂/Co@carbon nanotub (CNT) with oxygen-rich vacancies (OVs) can be obtained by annealing Ce-Co PBA at 700 °C. The microstructure study shows that carbon nanotubes will be catalyzed after annealing at high temperature, and the cobalt metal particles encapsulated in carbon nanotubes will be anchored in the matrix, regulating the impedance matching and multi-polarization suppression of the material, and its unique structure, vacancies, and strong interface effect make the material exhibit excellent electromagnetic wave (EMW) absorption performance. When the matching thickness is 2.5 mm, the minimum reflection loss (RL_min) of the composite is −51.68 dB, and the effective absorption bandwidth (RL < −10 dB) is 7.76 GHz. These results show that the prepared CeO₂/Co@CNT composite has excellent EMW absorption properties. It is expected to be a candidate material for EMW absorption.