Enhanced Photocatalytic H -Production Activity of CdS Quantum Dots Using Sn as Cocatalyst under Visible Light Irradiation.

Herein, oil-soluble CdS quantum dots (QDs) are first prepared through a solvent-thermal process. Then, oil-soluble CdS QDs are changed into water-soluble QDs via ligand exchange using mercaptopropionic acid as capping agent at pH 13. The photocatalytic performance is investigated under the visible light irradiation using glycerol as sacrificial agent and Sn as cocatalyst. No H -production activity is observed for oil-soluble CdS QDs. Water-soluble CdS QDs exhibit significantly enhanced hydrogen evolution rate. When the concentration of cocatalyst Sn increases to 0.2 × 10 m, the rate of hydrogen evolution reaches 1.61 mmol g h , which is 24 times higher than that of the pristine water-soluble CdS QDs. The enhanced H -production efficiency is attributed to the adsorption of Sn ions on the surface of CdS QDs that are further reduced to Sn atoms by photogenerated electrons. The in situ generated Sn atoms serve as photocatalytic cocatalyst for efficient hydrogen generation.