Cyclodextrin-Enhanced Photocatalytic Hydrogen Evolution Based on Formate Decomposition With Bio/Metal Catalysts.

Area of Science:

• Catalysis
• Photocatalysis
• Green Chemistry

Background:

• Formic acid is a safe hydrogen carrier, but efficient hydrogen release requires improved catalysts.
• Previous systems used toxic methyl viologen as an electron mediator.
• Acridinium complexes offer a safer alternative with long-lived charge-separated states.

Purpose of the Study:

• To develop a safer and more efficient photocatalytic system for hydrogen production from formic acid.
• To replace toxic mediators with a supramolecular complex of acridinium and cyclodextrins.
• To enhance photocatalytic activity in aqueous solutions.

Main Methods:

• Utilized supramolecular interactions (ionic, hydrophobic) to complex 9-Mesityl-10-methyl acridinium (Mes-Acr+) with cyclodextrins (CDs).
• Developed a hybrid system including formate dehydrogenase, NAD+, Mes-Acr+/CD complex, and platinum nanoparticles (Pt-PVP).
• Applied visible light to drive the photocatalytic hydrogen production reaction.

Main Results:

• The Mes-Acr+/CD supramolecular complex significantly improved photocatalytic activity in water.
• Achieved an ultimate yield of 24% for hydrogen production from formate at pH 6.0.
• Identified electron transfer from the Mes-Acr radical to Pt-PVP as the rate-determining step.

Conclusions:

• Supramolecular complexation of Mes-Acr+ with CDs enhances photocatalytic hydrogen production.
• The developed system offers a safer and effective alternative to previous methods using toxic mediators.
• Further optimization of electron transfer could improve overall hydrogen yield.