Deciphering Distinct Overpotential-Dependent Pathways for Electrochemical CO₂ Reduction Catalyzed by an...

Area of Science:

• Electrochemistry and Catalysis
• Computational Chemistry
• Materials Science

Background:

• Homogeneous electrocatalysts are crucial for efficient CO2 conversion.
• [Fe(tpyPY2Me)]2+ ([Fe]2+) exhibits exceptional performance in CO2 reduction to CO.
• Understanding the reaction mechanism is key to optimizing catalyst design.

Purpose of the Study:

• To elucidate the distinct mechanistic pathways of [Fe]2+ catalyzed CO2 electroreduction.
• To identify the origins of the catalyst's high selectivity and activity.
• To inform the rational design of next-generation electrocatalysts.

Main Methods:

• Combined experimental electrochemistry (controlled potential electrolysis) and computational studies.
• Analysis of catalytic regimes at varying overpotentials.
• Energetic span model for rate determination and mechanistic pathway validation.

Main Results:

• Two catalytic regimes were identified at low (<160 mV) and high (>590 mV) overpotentials.
• Low overpotential regime proceeds via an EECC mechanism involving [Fe]2+.
• High overpotential regime likely involves a proton-coupled electron-transfer (PCET) pathway via [Fe]+.

Conclusions:

• Synergistic computational and experimental approaches successfully deciphered complex electrocatalytic mechanisms.
• The PCET pathway is identified as dominant at higher overpotentials.
• Mechanistic insights pave the way for designing improved iron-based CO2 electrocatalysts.