Probe Binding Mode and Structure of the Photocatalytic Center: Hydrogen Generation by Quantum Dots and Nickel Ions

Artificial photosystems consisting of colloidal semiconductor quantum dots (QDs) and non-noble metal salts (e.g., Ni2+) show exceptional photocatalytic H-2 activity. Recent studies have found the structure of the catalysts distorted during the photocatalytic H-2 evolution reaction, which significantly influences the reaction kinetics. However, the in situ binding form between QDs and the catalytic center is still ambiguous. Herein, we reveal that, in the high-efficiency H-2 evolution photosystem based on CdS-S2- QDs and water-soluble Ni2+ salts (pH 6.0), the Ni-0 clusters formed in situ bind on the surface of QDs via a Ni-S bond to work as the real catalytic species for H-2 photogeneration, manifested by a combination of X-ray photoelectron spectroscopy, electron paramagnetic resonance, X-ray absorption spectroscopy, and a set of control experiments.

Automated summary

The study revealed the in situ binding form between QDs and Ni2+ salts in a high-efficiency H-2 evolution photosystem, demonstrating that Ni-0 clusters formed in situ on the surface of QDs via a Ni-S bond act as the real catalytic species for H-2 photogeneration.