Enhanced Photocatalytic H2 ‐Production Activity of CdS Quantum Dots Using Sn2+ as Cocatalyst under Visible Light Irradiation

Sn2+ greatly enhances the H2‐production activity of water‐soluble CdS quantum dots (QDs). Sn2+ ions are reduced to Sn atoms by the electrons generated from the conduction band of CdS quantum dots under visible light irradiation. Sn atoms not only serve as photocatalytic cocatalyst for hydrogen generation, but also participate in forming CdS/Sn Schottky heterojunction. AbstractHerein, 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 ligh t irradiation using glycerol as sacrificial agent and Sn2+ as cocatalyst. No H2‐production activity is observed for oil‐soluble CdS QDs. Water‐soluble CdS QDs exhibit significantly enhanced hydrogen evolution rate. When the concentration of cocatalyst Sn2+ increases to 0.2 × 10−3m, the rate of hydrogen evolution reaches 1.61 mmol g−1 h−1, which is 24 times higher than that of the pristine water ‐soluble CdS QDs. The enhanced H2‐production efficiency is attributed to the adsorption of Sn2+ 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.

Source: Small - July 1, 2020 Category: Nanotechnology Authors: Xianglin Xiang, Bicheng Zhu, Bei Cheng, Jiaguo Yu, Hongjin Lv Tags: Full Paper Source Type: research