Direct low concentration CO₂ electroreduction to multicarbon products via rate-determining step tuning

Area of Science:

• Electrochemistry
• Catalysis
• Materials Science
• Chemical Engineering

Background:

• Direct electrochemical conversion of dilute carbon dioxide (CO2) in industrial exhaust offers a sustainable CO2 utilization pathway, reducing separation costs.
• Challenges in dilute CO2 electrocatalysis include low conversion rates and weak adsorption of carbon intermediates, hindering the production of multi-carbon (C2+) products like ethylene.
• Optimizing catalyst interfaces is crucial for overcoming these limitations in CO2 electrolysis.

Purpose of the Study:

• To develop and optimize copper (Cu) catalysts with engineered Cu(111)/Cu2O(111) interface boundaries for efficient dilute CO2 electrocatalytic conversion.
• To investigate the effect of interface engineering on the rate-determining step and intermediate adsorption barriers in CO2 reduction.
• To enhance the selectivity and partial current density for C2+ products under low CO2 concentration conditions.

Main Methods:

• Fabrication of copper catalysts with controlled Cu(111)/Cu2O(111) interface boundary densities.
• Electrochemical characterization and testing of catalysts using a dilute CO2 feed (5% CO2 v/v).
• Analysis of reaction mechanisms to identify the rate-determining step under dilute CO2 conditions.

Main Results:

• Achieved a Faradaic efficiency of 51.9% ± 2.8% and a partial current density of 34.5 mA·cm-2 ± 6.4 mA·cm-2 for C2+ products.
• Demonstrated superior performance compared to state-of-the-art low-concentration CO2 electrolysis.
• Identified the generation of *COOH as the rate-determining step at the Cu0/Cu1+ interface boundary under dilute CO2 conditions, contrary to previous assumptions.

Conclusions:

• Interface boundary engineering of Cu catalysts is an effective strategy for enhancing dilute CO2 electrocatalytic conversion to C2+ products.
• The study reveals a shift in the rate-determining step to *COOH generation under dilute CO2 feed, providing new mechanistic insights.
• This work advances sustainable CO2 utilization by improving the efficiency and economics of converting industrial exhaust gases.