Transition Metal Disulfide Nanosheets Synthesized by Facile Sonication Method for the Hydrogen Evolution Reaction

Two-dimensional transition metal disulfide (TMD) nanosheets, including MoS2, WS2, TaS2, and TiS2, were used to catalyze the hydrogen evolution reaction (HER). The TMDs were exfoliated by sonication to generate nanosheet layers that were approximately a few hundred nanometers in size. X-ray diffraction and transmission electron microscope data indicated that the major plane of the exfoliated nanosheets was the (002) plane and that the hexagonal structure is maintained after exfoliation with lattice constants of 0.32 nm for MoS2 and WS2 and 0.34 nm for TaS2 and TiS2. Exfoliated MoS2, WS2, TaS2, and TiS2 loaded on Au electrodes exhibited good electrocatalytic activity with low onset potentials of ∼100, 150, 175, and 135 mV, respectively, at a current density of −1 mA/cm2. MoS2 and TiS2 exhibited the best HER performance with Tafel slopes of 94.91 and 91 mV/decade. These results indicated that TMD nanosheets have potential applications as HER catalysts for the mass production of hydrogen.