Activating basal-plane catalytic activity of two-dimensional MoS<inf>2</inf> monolayer with remote hydrogen plasma

Abstract

Two-dimensional layered transition metal dichalcogenide (TMD) materials such as Molybdenum disufide (MoS ) have been recognized as one of the low-cost and efficient electrocatalysts for hydrogen evolution reaction (HER). The crystal edges that account for a small percentage of the surface area, rather than the basal planes, of MoS monolayer have been confirmed as their active catalytic sites. As a result, extensive efforts have been developing in activating the basal planes of MoS for enhancing their HER activity. Here, we report a simple and efficient approach—using a remote hydrogen-plasma process—to creating S-vacancies on the basal plane of monolayer crystalline MoS ; this process can generate high density of S-vacancies while mainly maintaining the morphology and structure of MoS monolayer. The density of S-vacancies (defects) on MoS monolayers resulted from the remote hydrogen-plasma process can be tuned and play a critical role in HER, as evidenced in the results of our spectroscopic and electrical measurements. The H -plasma treated MoS also provides an excellent platform for systematic and fundamental study of defect-property relationships in TMDs, which provides insights for future applications including electrical, optical and magnetic devices. 2 2 2 2 2 2 2 2