Probing CO₂ Reduction Pathways for Copper Catalysis Using an Ionic Liquid as a Chemical Trapping Agent

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Developing efficient electrocatalysts is crucial for the electrochemical carbon dioxide reduction reaction (CO2RR) to support a sustainable solar-power economy.
• Current electrocatalyst development is hindered by a lack of mechanistic understanding, often relying on trial-and-error approaches.

Purpose of the Study:

• To demonstrate the utility of ionic liquids (ILs) as chemical trapping agents for elucidating CO2RR mechanistic pathways.
• To provide a novel method for understanding and controlling CO2RR product distribution.

Main Methods:

• Introduction of a specific ionic liquid, [BMIm][NTf2], as a chemical trapping agent to a copper foam electrocatalyst.
• Analysis of the impact of the IL on the selectivity of various CO2RR products, including formate, CO, alcohols, and hydrocarbons.

Main Results:

• The ionic liquid selectively suppressed the formation of ethylene, ethanol, and n-propanol, while minimally affecting other products.
• This selective suppression allowed for the disentanglement of reaction networks leading to different CO2RR products.
• New insights into the CO2RR mechanism were gained, offering guidance for catalyst and process optimization.

Conclusions:

• Ionic liquids serve as effective chemical trapping agents for probing electrocatalytic reaction mechanisms, specifically the CO2RR.
• This chemical trapping strategy enhances mechanistic understanding and provides a method to modulate CO2RR product selectivity.
• The approach is potentially applicable to other electrocatalytic reactions beyond CO2RR.