Semiconductor quantum dots (QDs) are attractive building blocks for photocatalytic hydrogen evolution because their optical and electronic properties can be tailored through nanoscale structural design. However, in many QD-based hybrid systems, limited interfacial coupling between the QDs and cocatalyst hinders charge transfer and obscures the relationship between the interfacial structure and function. Herein, we report a Ni-modified giant reverse type-I CdS/CdSe core/shell QD system prepared by photodeposition, in which the Ni loading can be quantitatively tuned from 1 to 7 atoms per QD. Structural and spectroscopic characterizations indicate that the deposited Ni species are intimately associated with the CdS/CdSe QDs, while the giant core/shell architecture is retained. This interfacial modification leads to systematic changes in charge-carrier behavior, as evidenced by photoluminescence, photocurrent, electrochemical impedance, transient photovoltage, and transient absorption measurements. Among the series, CdS/CdSe-Ni4 exhibits the most efficient visible-light-driven hydrogen evolution, with a rate of 4492 μmol g-1 h-1 and a turnover frequency of 2.6 s-1 per Ni site. The results show that the regulation of the QD/Ni interface plays an important role in promoting electron extraction and interfacial charge transfer. This study provides a useful model for understanding how surface metal-site modification influences the photophysical and photocatalytic properties of colloidal semiconductor core/shell nanostructures.
Wang et al. (Thu,) studied this question.