Abstract
Two-dimensional layered transition metal dichalcogenide (TMD) materials such as Molybdenum disufide (MoS2) 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 MoS2 monolayer have been confirmed as their active catalytic sites. As a result, extensive efforts have been developing in activating the basal planes of MoS2 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 MoS2; this process can generate high density of S-vacancies while mainly maintaining the morphology and structure of MoS2 monolayer. The density of S-vacancies (defects) on MoS2 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 H2-plasma treated MoS2 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.
The remote hydrogen-plasma can controllably create S-vacancies on basal planes of 2d MoS2 monolayers. Our electrical studies show that the MoS2 basal planes are activated without obvious degradation in crystalline morphologies. The treated MoS2 shows superior electrocatalytic properties, where the overpotential (183mV @10mA/cm2) and Tafel slope (77.6mV/dec) for hydrogen evolution reaction. [Display omitted]
•The remote hydrogen-plasma can controllably create S-vacancies on the basal planes of MoS2 monolayers.•Electrochemical studies show that the MoS2 basal planes are activated.•The H2-plasma treated MoS2 is an excellent platform for systematic and fundamental study of defect-property relations in TMDs.