In-situ growth of MoO2/MoS2 microspheres on reduced graphene oxide with enhanced dielectric polarization and impedance matching for boosting electromagnetic wave absorption

Abstract

Dielectric materials are promising candidates for electromagnetic wave (EMW) absorption due to the significant contribution of dielectric loss to EM energy dissipation. However, dielectric materials with single component usually exhibit limited EMW absorption performance because of their impedance mismatching and insufficient EMW attenuation capability. Reasonable designs of structure and composition are required to improve their EMW absorption performance. Herein, the rGO/MoO₂/MoS₂ (RMM) composite with MoO₂/MoS₂ heterogeneous microspheres grown in situ on reduced graphene oxide (rGO) is prepared through intermolecular hydrogen bonding and thermal reduction. The introduction of MoO₂/MoS₂ microspheres not only endows the composite with abundant mesopores and large specific surface area, but also facilitates the formation of heterogeneous interfaces and structural defects. By manipulating the relative component content of MoO₂ and MoS₂, RMM achieves excellent EMW absorption. At a relatively thin thickness of 1.70 mm, the reflection loss (RL) and effective absorption bandwidth of the composite reach −74.81 dB and 4.37 GHz. Correspondingly, the specific RL (RL/t) of the composite comes to −440.06 dB/cm, which is at the forefront among other typical dielectric microwave absorbers. This work provides a universal strategy to develop high-performance dielectric-type EMW absorption materials.