Electron Tunneling Fosters Solar-to-Hydrogen Energy Conversion.

Abstract

Transition-metal chalcogenide quantum dots (TMCs QDs) exhibit emerging potential in the field of solar energy conversion due to large absorption coefficients for light harvesting, quantum size effect, and abundant active sites. However, fine-tuning the photoinduced charge carrier over TMCs QDs to manipulate the directional charge-transfer pathway remains challenging, considering their ultrashort charge lifetime and slow charge-transfer kinetics. To this end, herein, MoSx/PDDA/TMCs QDs heterostructures were exquisitely designed by a simple and green electrostatic self-assembly strategy under ambient conditions, wherein tailor-made negatively charged TMCs QDs stabilized by mercaptoacetic acid (MAA) were precisely self-assembled on the positively charged polydiallyl dimethylammonium chloride (PDDA)-modified MoSx nanoflowers (NFs), forming a well-defined three-dimensional heterostructured nanoarchitecture. As an electron trapping agent, an MoSx NFs cocatalyst benefits the unidirectional electron transfer from TMCs QDs to the ideal active centers on the MoSx NFs surface by tunneling the ultrathin insulating polymer interim layer, thereby boosting the charge separation efficiency and endowing self-assembled MoSx/PDDA/TMCs QDs heterostructures with considerably increased photocatalytic hydrogen evolution activity (1.96 mmol·g-1·h-1) and admirable stability under visible light irradiation. Our work will provide new insights into smart regulation of directional charge transfer over TMCs QDs-based photosystems for solar energy conversion.