Stable Heterometallic Cluster-Based Organic Framework Catalysts for Artificial Photosynthesis

Area of Science:

• Materials Science
• Photocatalysis
• Green Chemistry

Background:

• Artificial photosynthesis aims to mimic natural processes for sustainable energy and chemical production.
• Metal-organic frameworks (MOFs) offer tunable structures for catalytic applications.
• Efficiently converting CO2 and H2O into valuable products like HCOOH and O2 remains a significant challenge.

Purpose of the Study:

• To design and synthesize novel heterometallic Fe2M cluster-based MOFs (NNU-31-M) for photocatalytic CO2 and H2O conversion.
• To investigate the photocatalytic performance and mechanism of these MOFs in achieving the overall artificial photosynthetic reaction.
• To establish a new strategy for designing crystalline photocatalysts for artificial photosynthesis.

Main Methods:

• Synthesis of heterometallic Fe2M cluster-based MOFs (NNU-31-M, M=Co, Ni, Zn).
• Photocatalytic experiments for CO2 and H2O conversion under visible light irradiation.
• Gas chromatography and other analytical techniques to quantify products (HCOOH, O2).
• Density Functional Theory (DFT) calculations to elucidate the reaction mechanism.

Main Results:

• NNU-31-M MOFs demonstrated efficient photocatalytic conversion of CO2 and H2O to HCOOH and O2 without sacrificial agents or photosensitizers.
• The heterometallic clusters and ligands generated separated electrons and holes upon visible light excitation, facilitating the redox reactions.
• NNU-31-Zn exhibited the highest HCOOH yield (26.3 μmol g⁻¹ h⁻¹) with nearly 100% selectivity.
• DFT calculations supported the proposed photocatalytic mechanism involving electron transfer to low-valent M and hole transfer to Fe.

Conclusions:

• The developed Fe2M MOFs represent the first MOF photocatalyst system capable of completing the full artificial photosynthetic reaction.
• This study provides a new design strategy for crystalline photocatalysts to achieve overall artificial photosynthesis.
• The findings open avenues for developing efficient and sustainable catalysts for CO2 utilization and renewable fuel production.