Electrochemical sulfidation of WS2 nanoarrays: Strong dependence of hydrogen evolution activity on transition metal sulfide surface composition

•Electrochemical sulfidation method used for non-MoS2 transition metal sulfides•Diminished HER activity but enhanced electron transfer after WS2 sulfidation•Sulfur incorporation only successful when electro-oxidation step forms soluble MxOY

The activity of transition metal sulfides for the hydrogen evolution reaction (HER) can be increased by sulfur-enrichment of active metal-sulfide sites. In this report, we investigate the electrochemical sulfidation of atmospherically aged WS2 nanoarrays with respect to enhancing HER activity. In contrast to MoS2, it is found that sulfidation diminishes HER activity. Electrochemical and XPS experiments suggest the involvement of insoluble tungsten oxides in the altered HER and electron transfer properties. This demonstrates the strong dependence of the transition metal dichalcogenide (TMD) composition with the successful sulfur incorporation and subsequent HER activity.

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