Molybdenum disulfide(MoS_2) has been acknowledged to play important roles in hydrogen evolution reaction(HER) for hydrogen energy technology. Both computational and experimental results have suggested that the promising catalytic activity of MoS_2 for the HER could be attributed to the sulfur edges of two-dimensional nanosheets, while their basal planes were catalytically inert. In order to verify this conclusion, we prepared single MoS_2 sheet electrodes which were made of individual MoS_2 sheets attached ...