Activation of MoS2 Basal Planes for Hydrogen Evolution by Zinc

Abstract

Molybdenum disulfide (MoS₂ ) has been widely studied as a potential earth-abundant electrocatalyst for the hydrogen-evolution reaction (HER). Defect engineering and heteroelemental doping are effective methods to enhance the catalytic activity in the HER, so exploring an efficient route to simultaneously achieve in-plane vacancy engineering and elemental doping of MoS₂ is necessary. In this study, Zinc, a low-cost and moderately active metal, has been used to realize this strategy by generation of sulfur vacancies and zinc doping on MoS₂ in one step. Density functional theory calculations reveal that the zinc atoms not only lower the formation energy of S vacancies, but also help to decrease ΔG_H of S-vacancy sites near the Zn atoms. At an optimal zinc-reduced MoS₂ (Zn@MoS₂ ) example, the activated basal planes contribute to the HER activity with an overpotential of -194 mV at 10 mA cm^-2 and a low Tafel slope of 78 mV/dec.

Keywords: basal plane activation; hydrogen evolution; molybdenum disulfide; sulfur vacancies; zinc reduction.