Understanding the Effect of *CO Coverage on C-C Coupling toward CO₂ Electroreduction

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Copper-based tandem nanocrystals are explored for multicarbon (C₂₊) product synthesis via CO₂ electroreduction.
• The precise relationship between *CO coverage and C-C coupling in these systems requires further elucidation.

Purpose of the Study:

• To construct and evaluate a tandem catalyst coupling Cobalt Phthalocyanine (CoPc) with a Copper Gas Diffusion Electrode (GDE).
• To investigate the mechanism of CO₂ electroreduction and C-C coupling influenced by *CO surface coverage.

Main Methods:

• Fabrication of a tandem catalyst: GDE of Cu-CoPc.
• Electrochemical CO₂ reduction experiments at a current density of 480 mA cm^-2.
• In situ spectroscopic studies and density functional theory (DFT) calculations.

Main Results:

• The GDE of Cu-CoPc achieved a 82% faradaic efficiency for C₂₊ products, 1.8 times higher than GDE of Cu.
• CoPc-induced high *CO coverage facilitated local *CO enrichment in a top adsorption mode.
• Reduced energy barrier for OCCO intermediate formation was observed, elucidating the C-C coupling pathway.

Conclusions:

• The GDE of Cu-CoPc demonstrates superior performance in CO₂ electroreduction to C₂₊ products.
• This study reveals a surface coverage-dependent, mode-specific C-C coupling mechanism crucial for efficient CO₂ conversion.