Defects Engineered Monolayer MoS₂ for Improved Hydrogen Evolution Reaction

TLDR

MoS₂ is a low‑cost, highly active, and stable electrocatalyst for hydrogen evolution, yet its efficiency is limited by the scarcity of active edge sites. This study shows that oxygen‑plasma and hydrogen treatments on pristine monolayer MoS₂ create defects that expose more edges, markedly boosting hydrogen evolution activity. Defects were introduced by plasma/hydrogen exposure and characterized across scales from macroscopic to atomic resolution. The defect‑engineering approach provides a facile route to enhance MoS₂‑based hydrogen production and deepens understanding of its catalytic behavior.

Abstract

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.