Conducting MoS₂ Nanosheets as Catalysts for Hydrogen Evolution Reaction

Abstract

We report chemically exfoliated MoS₂ nanosheets with a very high concentration of metallic 1T phase using a solvent free intercalation method. After removing the excess of negative charges from the surface of the nanosheets, highly conducting 1T phase MoS₂ nanosheets exhibit excellent catalytic activity toward the evolution of hydrogen with a notably low Tafel slope of 40 mV/dec. By partially oxidizing MoS₂, we found that the activity of 2H MoS₂ is significantly reduced after oxidation, consistent with edge oxidation. On the other hand, 1T MoS₂ remains unaffected after oxidation, suggesting that edges of the nanosheets are not the main active sites. The importance of electrical conductivity of the two phases on the hydrogen evolution reaction activity has been further confirmed by using carbon nanotubes to increase the conductivity of 2H MoS₂