In Situ Engineering of the Cu⁺/Cu⁰ Interface to Boost C₂₊ Selectivity in CO₂ Electroreduction

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• The Cu+/Cu0 interface is crucial for selective electrochemical reduction of carbon dioxide (ERCO2) to valuable C2+ products.
• Instability and oxidation of the Cu+/Cu0 interface pose challenges for catalyst design.
• In situ control of abundant and stable Cu+/Cu0 interfaces remains a significant hurdle.

Purpose of the Study:

• To develop a method for in situ synthesis of Cu-based electrocatalysts with abundant and stable Cu+/Cu0 interfaces.
• To investigate the role of trace halide ions in controlling the Cu+/Cu0 interface formation.
• To enhance the performance of electrocatalysts for the electrochemical reduction of carbon dioxide (ERCO2).

Main Methods:

• Density functional theory (DFT) calculations to understand reaction mechanisms.
• Experimental synthesis of CuO-derived electrocatalysts.
• Electrochemical characterization of catalyst performance for ERCO2.
• Analysis of product selectivity and Faraday efficiency.

Main Results:

• Trace halide ions adsorbed on Cu2O slow Cu+ → Cu0 reduction kinetics, enabling controlled in situ synthesis of Cu+/Cu0 interfaces.
• The engineered Cu catalyst achieved high Faraday efficiencies for C2H4 (55.8%) and C2+ products (75.7%) at -0.98 V vs RHE.
• Performance was ~16% higher than catalysts prepared without halide ions, attributed to improved CO-CO coupling and suppressed hydrogen evolution.

Conclusions:

• A simple and effective in situ engineering strategy using trace halide ions was developed for high-performance ERCO2 catalysts.
• This approach provides precise control over the Cu+/Cu0 interface, crucial for selective CO2 conversion.
• The findings offer a pathway for designing advanced electrocatalysts for sustainable chemical production.