Intercalated 2D MoS2 utilizing a simulated sun assisted process : reducing the HER overpotential

Molybdenum disulfide (MoS2) in its two-dimensional (2D) morphology has favorable catalytic properties for the hydrogen evolution reaction (HER). To fully take advantage of this capability and in order to enhance this materials HER performance, viable methods for synthesizing and tuning electronic properties of 2D MoS2 should be developed. Here, we demonstrate a facile and nonhazardous approach to partially intercalate Li+ ions into the 2D MoS2 host structure. We show that such an intercalation is possible in a nonhazardous saline Li+ containing solution using a grinding/sonication-assisted exfoliation method in both dark and simulated sun irradiation conditions. A partial phase transformation from semiconducting (2H) to metallic (1T) phase is observed for the majority of flakes, after the process. We observe a notable enhancement of the HER activity for samples prepared under light illumination in the presence of a Li+ containing solution, in comparison to both pristine 2D MoS2 samples and samples processed in the dark. This method provides an effective approach for phase engineering of 2D MoS2 for enhancing its HER performance.