Coverage-driven selectivity switch from ethylene to acetate in high-rate CO₂/CO electrolysis

Area of Science:

• Electrochemistry
• Catalysis
• Materials Science

Background:

• Electrolyte and organic modifications are known to improve CO2 electrolysis.
• The impact of mixed CO/CO2 feeds on catalyst microenvironments is not well understood.

Purpose of the Study:

• To investigate the effects of CO/CO2 co-electrolysis on CuO nanosheet catalysts.
• To understand how varying CO pressure influences product distribution and catalyst behavior.

Main Methods:

• Utilized CuO nanosheets in an alkaline membrane electrode assembly electrolyzer.
• Systematically varied CO partial pressure in the CO/CO2 feed gas.
• Analyzed product selectivity, Faradaic efficiency, and partial current density.

Main Results:

• Product distribution shifted from ethylene to acetate with increasing CO pressure.
• Optimized conditions yielded 90.0% Faradaic efficiency and 3.1 A cm-2 for multicarbon products.
• Achieved 100.0% carbon selectivity and 75.0% yield, surpassing thermocatalytic CO hydrogenation.
• Scale-up demonstrated high ethylene (457.5 ml min-1) and acetate (2.97 g min-1) formation rates.

Conclusions:

• Mixed CO/CO2 feeds offer a viable alternative for tuning catalyst microenvironments in CO2 electrolysis.
• This approach significantly enhances the production of valuable multicarbon chemicals.
• The study demonstrates a promising pathway for industrial CO2 utilization and chemical synthesis.