Synthesis Of Molybdenum Disulfide And The Photocatalysis Characteristics

Molybdenum disulfide (MoS2) with the graphite-like layered structure, is a typical representative of transition-metal sulfide, has been extensively studied in recent years. Crystals of MoS2 are composed of vertically stacked, in which the inter-layer atoms linked by covalent bonds and the S-Mo-S layers connected by weak Van der Waals forces. This unique structural characteristics lead to special physical and chemical properties of MoS2. It has been extensively studied recently and applied in hydrogen production, electronics, lubrication, lithium ion battery, and catalysis. The methods of preparing MoS2 mainly contains hydrothermal and solvothermal synthesis, chemical vapor deposition (CVD), and molecular beam epitaxy(MBE). Electronic properties of MoS2 varies with the thickness of different samples, the most significant aspect is the change of band structure. Bulk MoS2 is an indirect bandgap semiconductor with a bandgap of 1.2eV, whereas single layer MoS2 is an direct bandgap semiconductor with a bandgap of 1.8eV. This feature has aroused great interest in the scientific community. In this paper, we mainly study the MoS2 and MoS2/a-MoO3 heterostructures photocatalytic degradation characteristics, and also explore the MoS2 films by chemical vapor deposition conditions.1、Amorphous MoS2 microspheres are prepared by a simple one step hydrothermal synthesis firstly. Then, we use the as-prepared amorphous MoS2 microspheres as the precursor for the preparation of 2H-MoS2 nanoparticles. The phase compositions and crystallographic structures of the samples were examined by X-ray diffraction (XRD), field emission electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy. We also discuss the formation and growth mechanism of MoS2 microspheres. In addition, the photocatalytic properties of the two samples are investigated systematically.we find amorphous MoS2 microspheres has excellent visible photocatalytic activity for the degradation of rhodamine B (RhB). Finally, the possible photocatalytic degradation mechanisms of organic pollutants are discussed.2、In order to overcome the slow light corrosion of MoS2, MoS2/a-MoO3 heterojunction is designed. We prepare MoS2/α-MoO3 heterojunction and α-MoO3 nanoplates by heat treatment of the as-prepared amorphous MoS2 microspheres. Then phase compositions and crystallographic structures of the two samples are examined by XRD, SEM, TEM and Raman spectroscopy. A possible growth mechanism from amorphous MoS2 microspheres to α-MoO3 nanoplates is proposed. Moreover, photocatalytic properties of the two samples for the degradation of rhodamine B (RhB) under visible-light irradiation are studied, and in the meantime the corresponding possible photocatalytic degradation mechanisms are discussed.3、We synthesized high quality MoS2 films by direct vulcanization of MoO3. The effects of different growth conditions on MoS2 film quality are discussed and we find out the best way to prepare the MoS2 film. In addition, the structure and morphology of the MoS2 film investigated by optical microscopy, transmission electron microscopy and Raman spectroscopy, which provides theoretical basis for the growth of MoS2 film.