Modeling CO2 reduction on Pt(111).

Area of Science:

• Computational Chemistry
• Electrochemistry
• Surface Science

Background:

• Electrochemical reduction of carbon dioxide (CO2) is crucial for sustainable energy.
• Understanding reaction mechanisms on catalytic surfaces like platinum (Pt) is essential for efficient CO2 conversion.
• Previous studies have explored CO2 reduction, but detailed mechanistic insights into proton-electron transfer steps on Pt(111) remain an active area of research.

Purpose of the Study:

• To computationally model the electrochemical reduction of CO2 on a Pt(111) surface.
• To investigate the electronic energy barriers of the initial proton-electron transfer steps in CO2 reduction.
• To elucidate the factors contributing to low energy barriers in these elementary steps.

Main Methods:

• Density functional theory (DFT) calculations were employed.
• An explicit solvation layer and charged electrode conditions were simulated.
• Electronic energy barriers for four sequential proton-electron transfer steps were computed.

Main Results:

• Proton transfer to adsorbates, like CO2 to COOH, showed low energy barriers (~0.1 eV).
• Steps involving simultaneous C-O bond cleavage and proton transfer had higher barriers (~0.5 eV).
• All calculated barriers were found to be surmountable at room temperature.

Conclusions:

• The calculated low energy barriers suggest that CO2 reduction on Pt(111) is kinetically feasible.
• Decoupled electron and proton transfer, along with initial charge localization, contribute to the reduced activation energies.
• The findings provide fundamental insights into the CO2 electroreduction mechanism on platinum surfaces.