Electronic Supporting Information Remarkable Activity and Stability of Photocatalytic Hydrogen Production over Dye-Sensitized Single Molecular Layer MoS2 Ensemble Experimental Preparation of S-MoS2 Single-layer MoS2 was synthesized by the exfoliation of MoS2 with lithium

Remarkable Activity and Stability of Photocatalytic Hydrogen Production over Dye-Sensitized Single Molecular Layer MoS2 Ensemble Experimental Preparation of S-MoS2 Single-layer MoS2 was synthesized by the exfoliation of MoS2 with lithium intercalation[1]. The starting material used in the reported studies was bulk MoS2 powder from Sigma Aldrich. 500 mg of the black MoS2 powder was first soaked in 8 mL of 1.6 M n-butyl lithium in hexane for 48 hours under nitrogen atmosphere. Following the intercalation of the MoS2 by lithium, the produced LixMoS2 was washed repeatedly with hexane to remove the excess butyl-lithium and dried under nitrogen atmosphere. Then the powder was immersed in water and the suspension was ultrasonicated during the reaction to assist in the exfoliation. It was assumed that the reaction between the water and the intercalated lithium forms hydrogen gas between the layers, and the expansion of this gas tends to separate the MoS2 layers. As the reaction proceeded more deeply into each crystallite, the layers became further separated. Eventually the layers became completely separated and remain suspended in the aqueous solution. The pH of this solution was basic due to the presence of lithium hydroxide.