Multivariate Tuning of Photosensitization in Mixed-Linker Metal-Organic Frameworks for Efficient CO₂ Reduction

Area of Science:

• Materials Science
• Catalysis
• Photochemistry

Background:

• Photosensitization enhances photocatalyst performance by improving light absorption, energy transfer, and charge separation.
• Achieving high efficiency in heterogeneous systems requires precise control over photosensitizers, catalytic centers, and their interactions, which is challenging.

Purpose of the Study:

• To develop multivariate metal-organic frameworks (MOFs) with tunable defects for precise control over photosensitizers, catalytic centers, and their ratios.
• To create an efficient platform for carbon dioxide (CO2) reduction using these engineered MOFs.

Main Methods:

• Synthesized multivariate zirconium MOFs incorporating triphenylamine, phenoxazine, or phenothiazine-based linkers as photosensitizers.
• Integrated metal porphyrin linkers (Fe, Co, Ni, Zn) as CO2 reduction catalytic centers.
• Utilized the defect tolerance of Zr6 nodes to systematically vary linker ratios by introducing missing linker defects.

Main Results:

• Achieved CO2-to-CO reduction rates of 247.8 μmol gcat.-1 h-1, a 17-fold enhancement over homogeneous analogues.
• Demonstrated unprecedented control over photosensitizer, catalytic metal center, and their ratios within the MOF structure.
• Transient spectra and DFT calculations confirmed efficient intrareticular energy transfer and charge separation.

Conclusions:

• Multivariate MOFs with tunable defects offer a unique platform for optimizing photocatalyst performance.
• This approach enables precise control over key components for advanced artificial photosynthetic systems.
• The engineered MOFs significantly advance the efficiency of CO2 reduction catalysis.