Defects Engineered Monolayer MoS₂ for Improved Hydrogen Evolution Reaction

MoS₂ is a promising and low-cost material for electrochemical hydrogen production due to its high activity and stability during the reaction. However, the efficiency of hydrogen production is limited by the amount of active sites, for example, edges, in MoS₂. Here, we demonstrate that oxygen plasma exposure and hydrogen treatment on pristine monolayer MoS₂ could introduce more active sites via the formation of defects within the monolayer, leading to a high density of exposed edges and a significant improvement of the hydrogen evolution activity. These as-fabricated defects are characterized at the scale from macroscopic continuum to discrete atoms. Our work represents a facile method to increase the hydrogen production in electrochemical reaction of MoS₂ via defect engineering, and helps to understand the catalytic properties of MoS₂.