Stabilizing Cu^δ+ Sites via Bidentate Coordination toward Efficient Electrochemical C-C Coupling

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Copper electrocatalysts are key for CO2 reduction reaction (CO2RR) but suffer from poor ethanol selectivity.
• Variable copper oxidation states lead to undesired CO desorption or C2+ product formation.

Purpose of the Study:

• To stabilize Cu active sites and improve selectivity towards ethanol in the electrocatalytic CO2 reduction reaction (eCO2RR).
• To investigate the role of ligand-mediated coordination in regulating Cu catalysts for enhanced performance.

Main Methods:

• Immobilization of highly dispersed Cu active sites within a polyacrylic acid (PAA) matrix (PAA-Cu electrocatalyst).
• Stabilization of Cuδ+ (0 < δ < 1) sites through bidentate chelation with carboxylate ligands.
• Density functional theory (DFT) calculations to elucidate reaction mechanisms.

Main Results:

• The PAA-Cu electrocatalyst achieved a high Faradaic efficiency of 61.9% for ethanol production.
• Achieved ethanol selectivity was approximately double that of unmodified Cu nanoparticle electrodes (31.2%).
• Stable electrocatalytic operation was maintained for approximately 28 hours.

Conclusions:

• Ligand-mediated coordination engineering is crucial for regulating Cu active sites in eCO2RR.
• Stabilized Cuδ+ sites facilitate specific CO coupling pathways, favoring selective ethanol synthesis.
• The PAA-Cu system offers a promising strategy for efficient and selective electrochemical CO2 conversion to ethanol.