Optimizing the Performance of Low-Loaded Electrodes for CO₂-to-CO Conversion Directly from Capture Medium: A...

Area of Science:

• Electrochemistry
• Catalysis
• Carbon Capture and Utilization (CCU)

Background:

• Gas-fed reactors for CO2 reduction require energy-intensive CO2 separation from flue gas.
• Bicarbonate flow reactors integrate carbon capture and valorization, converting CO2 capture media into valuable chemicals like CO.
• This approach bypasses the need for expensive CO2 separation processes.

Purpose of the Study:

• To investigate the influence of electrode structure on bicarbonate reactor performance.
• To analyze the effects of catalyst mass loading and electrode permeability on Faradaic efficiency, activity, and CO2 utilization.
• To introduce electrochemical impedance spectroscopy for analyzing bicarbonate electrolyzers.

Main Methods:

• Investigated three commercial carbon supports to study catalyst mass loading and electrode permeability.
• Employed sputtering deposition to fabricate novel silver-based electrodes.
• Utilized electrochemical impedance spectroscopy to deepen understanding of bicarbonate electrolysis.

Main Results:

• Optimized silver mass loading from 116 μg/cm² to 565 μg/cm² enhanced selectivity (55% to 77%) and activity.
• Increased electrode permeability doubled reactor activity and boosted in situ CO2 production by 40%.
• Achieved near 80% Faradaic efficiency for CO production with optimized Ag-electrode (565 μg/cm² loading) at 3 V and ambient conditions.

Conclusions:

• Electrode structure, specifically catalyst loading and permeability, significantly impacts bicarbonate reactor performance.
• A novel, low-loaded silver electrode fabricated via sputtering deposition offers improved CO2 valorization.
• The optimized electrode design represents a significant advancement in efficient and cost-effective CO2 reduction technologies.