Acidic-alkaline tandem system for durable CO₂-CO-C₂

Area of Science:

• Electrochemistry
• Catalysis
• Materials Science

Background:

• Tandem carbon dioxide reduction reaction (CO2RR) to multicarbon products (C2+) is crucial for carbon valorization.
• Conventional alkaline or neutral systems suffer from limited CO2 utilization and stability due to (bi)carbonate formation.

Purpose of the Study:

• To design a durable acidic-alkaline tandem system for efficient synthesis of C2+ products, particularly ethylene.
• To overcome the limitations of conventional CO2RR systems.

Main Methods:

• Developed a catalyst with controlled metal site distance for the acidic CO2RR step to regulate *COOH adsorption.
• Integrated this catalyst into an acidic-alkaline tandem system coupled with alkaline carbon monoxide electroreduction.

Main Results:

• Achieved 99.7% Faradaic efficiency for carbon monoxide in the acidic step using a catalyst with 0.5 nm nickel sites.
• Attained 75.3% ethylene and 92.5% C2+ Faradaic efficiency at 10 A in the tandem system.
• Demonstrated stability for 400 hours.

Conclusions:

• The designed acidic-alkaline tandem system efficiently converts CO2 to C2+ products with high selectivity and durability.
• This work offers solutions for catalyst and electrolyzer design for sustainable CO2 conversion.