Lateral Adsorbate Interactions Inhibit HCOO^- while Promoting CO Selectivity for CO₂ Electrocatalysis on Silver

Area of Science:

• Electrochemistry
• Surface Science
• Catalysis

Background:

• Silver (Ag) is a promising catalyst for electrochemical reduction of carbon dioxide (CO2 ER) to carbon monoxide (CO).
• Discrepancies exist between theoretical models and experimental results for Ag-catalyzed CO2 ER.
• Understanding reaction intermediates is crucial for optimizing catalyst performance.

Purpose of the Study:

• Investigate the role of the formate intermediate (*OCHO) in Ag-catalyzed CO2 ER.
• Resolve the discrepancy between theoretical predictions and experimental outcomes for Ag catalysts.
• Elucidate the mechanism governing selectivity towards CO production.

Main Methods:

• Theoretical calculations to model reaction pathways and intermediate binding.
• In situ surface-enhanced Raman spectroscopy (SERS) to detect surface species.
• Analysis of intermediate interactions and their effect on surface coverage.

Main Results:

• The formation of *OCHO is favored on Ag surfaces due to solvation and binding strength.
• In situ SERS provides preliminary evidence for O-bound bidentate species attributed to *OCHO.
• *OCHO formation competes with *H formation, influencing subsequent reaction steps.
• Lateral interactions involving *OCHO inhibit formate and H2 production, enhancing CO selectivity.

Conclusions:

• The formate intermediate (*OCHO) plays a critical role in Ag-catalyzed CO2 electroreduction.
• Understanding *OCHO's behavior is key to resolving performance discrepancies in Ag catalysts.
• This work provides insights into optimizing Ag for selective CO production from CO2.