Effects of precursor concentration on morphology of MoS₂ nanosheets by hydrothermal synthesis

MoS₂ nanosheets were fabricated with different precursor concentrations to investigate their effects on crystal structure, chemical state of elements, and morphology. MoS₂ nanosheets were prepared by conventional hydrothermal routes at 200°C for 24 h, while maintaining the Mo/S precursor mol ratio of 1:12. The XRD and XPS analyses showed that a hexagonal structure of 2H-MoS₂ nanosheets was formed without a second phase for all samples and crystallinity was enhanced along the c-axis with increasing precursor concentration. The FESEM and TEM images revealed that MoS₂ nanosheets were aggregated and formed nanoflowers, and that their irregular shape changed to nearly spherical as the concentration increased. The size of the nanoflowers was closely related to the dimension of the nanosheets and their sizes slightly increased with increasing concentration ranging from 0.14 M to 0.7 M, then rapidly increased at 1.4 M. We believe that these results are related to not only the enhanced growth rate but also the decreased additives-absorption on the S layers with precursor concentration.