Why Including Solvation is Paramount: First-Principles Calculations of Electrochemical CO₂ Reduction to CO on a Cu...

Area of Science:

• Electrochemistry
• Computational Chemistry
• Materials Science

Background:

• Electrochemical reduction of carbon dioxide (CO2) to valuable chemicals is a promising strategy for energy and environmental solutions.
• Copper-based catalysts are key for CO2 electroreduction to CO.
• Understanding reaction pathways is crucial for catalyst design and process optimization.

Purpose of the Study:

• To comprehensively map the electrochemical reduction of CO2 to CO on Cu(100).
• To investigate the influence of solvent effects, particularly water, on the reaction pathway and energetics.
• To compare the performance of water as a solvent against other options.

Main Methods:

• First-principles simulations were employed to map reaction pathways, including intermediates and transition states.
• The reaction was studied both in vacuum and with explicit water molecules to assess solvent effects.
• Thermodynamic favorability and spontaneous behavior were analyzed at different applied potentials.

Main Results:

• The CO2 reduction reaction to CO on Cu(100) was initiated at -0.11 V (RHE) and became spontaneous at -1.24 V (RHE).
• Solvation effects significantly alter adsorbate stability, lower energy barriers, and change kinetic and energetic parameters.
• The primary pathway for CO production was identified as CO2 →trans-COOH*→cis-COOH*→CO*+OH*→CO*→CO.

Conclusions:

• Explicit inclusion of water molecules is critical for accurate simulation of eCO2RR, challenging the simplification of vacuum pathways.
• Water is presented as a sustainable and cost-effective solvent compared to organic solvents, ionic liquids, and mixed systems.
• This study provides fundamental insights into CO2 electroreduction mechanisms, aiding in the development of efficient catalysts and processes.