Hierarchical 3D flower-like MoS2 spheres: Post-thermal treatment in vacuum and their NO2 sensing properties

Abstract Hierarchical 3D flower-like MoS 2 spheres were first synthesized by a facile hydrothermal process. Afterwards, MoS 2 spheres were annealed in vacuum under an Ar atmosphere to prevent MoS 2 partial oxidation in the MoO 3 form. As-prepared MoS 2 samples were characterized by XRD, EDS, SEM, TEM and BET. SEM images showed that the flower-like spheres were about 1–2 µm in diameter and built up with MoS 2 thin sheets. Moreover, there were many mesoporous structures consisting of nanosheets on the surface of the MoS 2 spheres. The resulting NO 2 gas sensor displayed a high sensitivity, good reproducibility and selectivity. A possible NO 2 gas sensing mechanism of MoS 2 spheres was preliminarily proposed.