Theoretical Insights into a CO Dimerization Mechanism in CO2 Electroreduction

Area of Science:

• Electrochemistry
• Materials Science
• Computational Chemistry

Background:

• Copper (Cu) is a key catalyst for CO2 electroreduction, but the mechanism of C-C coupling remains under investigation.
• Understanding intermediate stabilization is crucial for optimizing catalytic activity and selectivity.

Purpose of the Study:

• To investigate the catalytic role of copper in carbon monoxide (CO) dimerization during CO2 electroreduction using DFT simulations.
• To identify novel intermediates and reaction pathways governing C-C coupling on copper surfaces.

Main Methods:

• Density Functional Theory (DFT) simulations were employed to model CO adsorption and dimerization on Cu(111) and Cu(100) surfaces.
• The influence of a charged water layer and various cations on reaction energetics and activation barriers was systematically studied.

Main Results:

• A previously unreported CO dimer configuration, stabilized by a charged water layer, was identified on both Cu(111) and Cu(100).
• This charged water layer is essential for the thermodynamic feasibility of CO dimer formation.
• Lower activation barriers for dimerization on Cu(100) compared to Cu(111) align with experimental observations of higher C-C coupling activity.

Conclusions:

• The charged water layer plays a critical role in stabilizing CO dimers, facilitating C-C coupling in CO2 electroreduction on copper.
• The superior performance of Cu(100) for C-C coupling is attributed to lower activation barriers and favorable adsorption energetics.
• The findings are consistent with experimental observations, including the pH independence of C2 formation, due to the presence of other cations.