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.