Sulfur-vacancy engineering of natural molybdenite for enhanced EMW absorption

The fine processing and functional application of natural minerals are crucial for allowing the comprehensive utilization of natural mineral resources. This paper reports the modification of natural molybdenite: S-vacancies are used to promote the attenuation of electromagnetic waves (EMWs) in molybdenite matrix composites, thus improving the EMW absorption performance of molybdenite. First, S-vacancies are constructed on the base plane of molybdenite (MoS(2-x)) via treatment with NaBH4. The generated S-vacancies are found to change the original electronic layout, reduce the energy gap, and increase the probability of charge transfer within molybdenite. Concomitantly, the introduction of S-vacancies increases the number of active sites for interfacial and defecs polarization in molybdenite. MoS(2-x)-1 shows a higher absorption performance, with a minimum reflection loss (RLmin) of -34.35 dB (the absorbing layer thickness is 2.1 mm). The attenuation of EMWs by MoS(2-x) is attributed to a dielectric loss mechanism in which the polarization loss is dominant, and the increase in internal charge transfer promotes conductive loss. The findings of this study greatly expand the application scope of pure natural molybdenite and will facilitate the industrial production of high-performance EMW-absorbing materials and improve the comprehensive utilization of mineral resources.