Two-dimensional (2D) layered transition metal dichalcogenides (TMDCs) have attracted a lot of interest recently. MoS2 is a typical example that has two polytypes: stable 2H phase and meta-stable 1T phase. The 1T-MoS2 phase exhibits high hydrogen evolution reaction (HER) activity, despite its meta-stability. We computationally explored stabilization of the 1T phase by chemical functionalization on the sulfur layers and found that the 1T phase becomes more stable than the 2H phase after some crossover coverage. In addition, we examined the HER mechanism on the basal plane of 1T MoS2 phase by calculating the kinetic barriers for the three elementary steps (Volmer, Heyrovsky and Tafel) involved in the HER process and found lower overpotential on the 1T phase. Our results shed light on the higher HER activity of the 1T phase.

Chemical stabilization and mechanism of hydrogen evolution reaction, 1T MoS2

251st National Meeting (2016)

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