Synthesis of polymorphic CoSe2@MoSe2 microspheres with hollow and core-shell structures for electromagnetic wave absorption

Structure design and surface morphology control are effective strategies for preparing electromagnetic wave absorbing (EWA) materials with superior performance. In this work, Co microspheres with large diameters and rough surfaces were prepared by a simple solvothermal reaction. Then, through a one-pot hydrothermal reaction with Se and Mo sources, the Co was changed into polymorphic CoSe2 and loaded with a layer of MoSe2 nanosheets. Moreover, as the Co cations migrated outside to react with Se, free space was generated inside the spheres; thus, hollow and core-shell structures were achieved. The synthesized CoSe2@MoSe2 complex can cause dielectric and magnetic loss at the same time, achieving a minimum reflection loss of -45 dB and a maximum effective absorption bandwidth of 6 GHz. This work provides insight regarding the utility and massive synthesis of Co microspheres and advanced EWA materials with unique structures and diverse loss modes.