Tuning the MoS₂ Edge-Site Activity for Hydrogen Evolution via Support Interactions

Abstract

The hydrogen evolution reaction (HER) on supported MoS₂ catalysts is investigated using periodic density functional theory, employing the new BEEF-vdW functional that explicitly takes long-range van der Waals (vdW) forces into account. We find that the support interactions involving vdW forces leads to significant changes in the hydrogen binding energy, resulting in several orders of magnitude difference in HER activity. It is generally seen for the Mo-edge that strong adhesion of the catalyst onto the support leads to weakening in the hydrogen binding. This presents a way to optimally tune the hydrogen binding on MoS₂ and explains the lower than expected exchange current densities of supported MoS₂ in electrochemical H₂ evolution studies