Decoupling Charge Carrier Electroreduction and Enzymatic CO₂ Conversion to Formate Using a Dual-Cell Flow Reactor...

Area of Science:

• Electrochemistry
• Biocatalysis
• Sustainable Chemistry

Background:

• Formic acid (FA) is a valuable fuel derived from CO2, crucial for fuel cells and hydrogen storage.
• Traditional metal catalysts for CO2 conversion to FA face challenges with side reactions and long-term product recovery.
• Enzymatic catalysis offers a promising alternative for selective and efficient CO2 conversion.

Purpose of the Study:

• To develop and optimize an enzymatic catalytic system for the selective electrochemical conversion of carbon dioxide (CO2) to formate.
• To enhance the stability and production yield of formate using a dual-cell flow reactor system.
• To investigate the impact of system design configurations on long-term performance and efficiency.

Main Methods:

• Utilized a dual-cell flow reactor system with electrochemical reduction of a charge mediator to activate an enzymatic catalyst.
• Employed a pH control pump to maintain optimal catalyst activity and a packed bed reactor for improved charge carrier-catalyst contact.
• Monitored formate production, Coulombic efficiency, and catalyst stability over extended operational periods (approximately 168 hours).

Main Results:

• Achieved a formate production of 25 mM with over 50% Coulombic efficiency.
• The dual-cell system demonstrated improved formate yield compared to batch systems and minimized enzyme degradation.
• Optimized configurations with pH control and packed bed reactors maintained high production and efficiency over long-term operation.

Conclusions:

• The enzymatic dual-cell system effectively converts CO2 to formate, showcasing potential for sustainable fuel production.
• The study highlights the complex interplay of parameters in optimizing electrochemical CO2 conversion systems.
• Further improvements to this configuration hold promise for various electrochemical CO2 utilization applications.