Anchoring Ni Sites on "Giant" Reverse Type-I CdS/CdSe Core/Shell Quantum Dots for Visible-Light-Induced Hydrogen...

Area of Science:

• Materials Science
• Nanotechnology
• Photocatalysis

Background:

• Semiconductor quantum dots (QDs) offer tunable properties for photocatalysis.
• Interfacial coupling in QD-cocatalyst systems often limits charge transfer and hinders performance.

Purpose of the Study:

• To investigate the impact of Ni modification on CdS/CdSe core/shell QDs for photocatalytic hydrogen evolution.
• To understand the relationship between interfacial structure and photocatalytic function.

Main Methods:

• Photodeposition of Ni onto CdS/CdSe core/shell QDs with tunable loading.
• Characterization using structural and spectroscopic techniques (photoluminescence, photocurrent, electrochemical impedance, transient photovoltage, transient absorption).

Main Results:

• Successfully prepared Ni-modified CdS/CdSe QDs with controlled Ni loading (1-7 atoms per QD).
• Demonstrated intimate association of Ni with QDs while preserving core/shell structure.
• Observed systematic changes in charge-carrier behavior with Ni modification.
• CdS/CdSe-Ni₄ showed the highest visible-light-driven hydrogen evolution rate (4492 μmol g⁻¹ h⁻¹) and turnover frequency (2.6 s⁻¹ per Ni site).

Conclusions:

• Optimizing the QD/Ni interface is crucial for efficient electron extraction and interfacial charge transfer.
• Surface metal-site modification significantly influences the photophysical and photocatalytic properties of semiconductor nanostructures.
• This work provides a model system for studying interfacial effects in QD-based photocatalysts.