Polyoxometalate-based nickel clusters as visible light-driven water oxidation catalysts

Area of Science:

• Inorganic Chemistry
• Materials Science
• Photocatalysis

Background:

• Polyoxometalates (POMs) are versatile inorganic clusters with tunable properties.
• Nickel-based clusters are of interest for catalytic applications, including water oxidation.
• Mimicking natural photosynthetic systems, like photosystem II, is a key goal in artificial photosynthesis.

Purpose of the Study:

• To synthesize and characterize new polyoxometalate-based polynuclear nickel clusters.
• To investigate the photocatalytic activity of these novel clusters for visible light-driven water oxidation.
• To establish a new structural model for efficient all-inorganic water oxidation catalysts.

Main Methods:

• Synthesis and structural characterization of three new nickel-polyoxometalate clusters.
• Visible light-driven water oxidation experiments using the synthesized clusters as homogeneous catalysts.
• Confirmation of catalyst identity and stability using dynamic light-scattering, UV-vis absorption, and electrophoretic measurements.

Main Results:

• Three new POM-based nickel clusters with {Ni12}, {Ni13}, and {Ni25} cores were successfully synthesized.
• The largest cluster, {Ni25}, represents a new size record for POM-based nickel clusters.
• All synthesized clusters exhibited good photocatalytic activity for water oxidation, with high turnover numbers (up to 204.5 for cluster 3).
• Experimental evidence confirmed that the synthesized clusters, not simple nickel ions or oxides, were the active catalysts.

Conclusions:

• The study presents a new class of all-inorganic polynuclear nickel clusters based on POMs.
• These novel clusters serve as efficient homogeneous catalysts for visible light-driven water oxidation.
• The findings provide a promising structural model for developing advanced artificial photosynthesis systems.