Morphological Evolution of Vertically Standing Molybdenum Disulfide Nanosheets by Chemical Vapor Deposition

In this study, we demonstrated the chemical vapor deposition (CVD) of vertically standing molybdenum disulfide (MoS2) nanosheets, with an unconventional combination of molybdenum hexacarbonyl (Mo(CO)6) and 1,2-ethanedithiol (C2H6S2) as the novel kind of Mo and S precursors respectively. The effect of the distance between the precursor’s outlet and substrates (denoted as d) on the growth characteristics of MoS2, including surface morphology and nanosheet structure, was investigated. Meanwhile, the relationship between the structure characteristics of MoS2 nanosheets and their catalytic performance for hydrogen evolution reaction (HER) was elucidated. The formation of vertically standing nanosheets was analyzed and verified by means of an extrusion growth model. The crystallinity, average length, and average depth between peak and valley (Rz) of MoS2 nanosheets differed depending on the spatial location of the substrate. Good crystalized MoS2 nanosheets grown at d = 5.5 cm with the largest average length of 440 nm, and the highest Rz of 162 nm contributed to a better HER performance, with a respective Tafel slope and exchange current density of 138.9 mV/decade, and 22.6 μA/cm2 for raw data (127.8 mV/decade and 19.3 μA/cm2 for iR-corrected data).