Constructing uniform Fe3O4@C@MnO2 microspheres with yolk-shell interior toward enhancement in microwave absorption

Abstract

An efficient strategy for the synthesis of the rational designed yolk-shell microspheres with hollow Fe3O4 core and carbon@MnO2 double shell has been developed in this study. Hollow Fe3O4@SiO2 microspheres were firstly synthesized as template, and then yolk-shell Fe3O4@carbon@MnO2 microspheres were obtained by a series of processes including coating, carbonization and etching. The results showed that Fe3O4@carbon@MnO2 composite samples exhibited outstanding electromagnetic wave absorption performance. It is worth noting that the optimal RL value of Fe3O4@carbon@MnO2 composites could be achieved −58.25 dB at 5.56 GHz with a thickness of 4.2 mm and the absorption bandwidth for RL < −10 dB could range from 8.24 GHz to 13.68 GHz (5.44 GHz) with a thickness of 2.65 mm. The superior electromagnetic wave absorption performance can benefit from the hollow yolk-shell structure, and the effective complementary Fe3O4 core and the carbon@MnO2 double-layer shells by multiple reflection, strong polarization loss and conduction loss. Therefore, forming yolk-shell microsphere with hollow Fe3O4 core and carbon@MnO2 double layer shells is an efficient strategy to significantly enhance the microwave absorption performance of the absorber. The established yolk-shell Fe3O4@carbon@MnO2 composites is a promising absorbing material with strong absorption ability and wide effective absorbing bandwidth.