Structural engineering and compositional manipulation for high-efficiency electromagnetic microwave absorption

Abstract

Structural engineering and component modulation are effective strategies for designing superior electromagnetic wave (EMW) absorbing materials. The challenge of understanding the structure-component-property relationship and developing efficient microwave absorbers, however, remains a huge challenge. In this work, we demonstrate a microemulsion phase transition approach to the design of different structures of dielectric microwave absorbing materials. Three different structures of MoO2/C (MC) microspheres, solid, yolk-shell, and hollow can be prepared by regulating the ratio of the two phases of water and oil. The MoO2/MoS2/C (MSC) trilayer dielectric microspheres with Schottky barriers were prepared by a subsequent vulcanization process in which component modulation allowed the construction of multi-interfaces and vacancy engineering. The analysis reveals that the sensitivity of the different structures to component modulation varies considerably, mainly in the number of vacancies generated by the sulfidation process. This difference is determined by both the free space of the microspheres and the number of effective media. Such a phenomenon provides insight into the interplay between structure and components in attenuating EMW. Of these, with the 50% sulfated MoO2/MoS2/C yolk-shell microspheres (YSMSC) exhibiting a reflection loss (RL) of −80.73 dB at a thin thickness of 1.7 mm; the fully sulfated MoS2/C hollow microspheres (HMSC) achieve an effective absorption bandwidth (EAB) of 7.04 GHz at 2.2 mm. Our study contributes to an in-depth understanding of the structure-component-property relationship of EMW absorbers and provides a reference for tuning the product structure using microemulsion phase conversion methods.