Pure and stable metallic phase molybdenum disulfide nanosheets for hydrogen evolution reaction

摘要

Metallic-phase MoS₂ (M-MoS₂) is metastable and does not exist in nature. Pure and stable M-MoS₂ has not been previously prepared by chemical synthesis, to the best of our knowledge. Here we report a hydrothermal process for synthesizing stable two-dimensional M-MoS₂ nanosheets in water. The metal–metal Raman stretching mode at 146?cm?1 in the M-MoS₂ structure, as predicted by theoretical calculations, is experimentally observed. The stability of the M-MoS₂ is associated with the adsorption of a monolayer of water molecules on both sides of the nanosheets, which reduce restacking and prevent aggregation in water. The obtained M-MoS₂ exhibits excellent stability in water and superior activity for the hydrogen evolution reaction, with a current density of 10?mA?cm?2 at a low potential of ?175?mV and a Tafel slope of 41?mV per decade.