Effects of excess sulfur source on the formation and photocatalytic properties of flower-like MoS2 spheres by hydrothermal synthesis

Flower-like MoS2 spheres were successfully prepared via a facile hydrothermal method. The effects of excess sulfur on the formation of MoS2 were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The XRD pattern showed that the preferential orientation of the flower-like hexagonal 2H-MoS2 spheres was the (002) plane, and I002/I100 ratio values indicated that the (002) plane grew more completely than the (100) plane with increasing S/Mo ratio. The FESEM images revealed that the sheet thickness of the MoS2 spheres increased to ~30 nm with increasing S/Mo ratio, exposing more edges on the nanosheets of the MoS2 spheres. Photocatalytic properties of the products were studied, and the results showed that the MoS2 sample with a S/Mo ratio of 2.75 exhibited the highest degradation rate constant and methylene blue degradation rate under 90 min visible light irradiation. The results showed that the enhancement of photocatalytic activity originated from increasing exposed area of the {100} facets with increasing S/Mo ratio under the hydrothermal environment.