Identifying Intermediates in CO₂-to-C₂H₄ Electrochemical Reduction by In Situ Surface-Enhanced Raman Spectroscopy

Area of Science:

• Electrochemistry
• Materials Science
• Spectroscopy

Background:

• Electrochemical carbon dioxide reduction (CO2RR) is crucial for producing value-added C2+ products.
• In situ spectroscopy is vital for understanding CO2RR mechanisms by identifying key intermediates.

Purpose of the Study:

• To investigate CO2RR pathways on Cu2O using a "borrowing" surface-enhanced Raman spectroscopy (SERS) strategy.
• To correlate CO intermediate binding modes with electrochemical selectivity in neutral and alkaline electrolytes.

Main Methods:

• Utilized core-shell Au@Cu2O nanocatalysts with varying shell thicknesses.
• Employed in situ Raman spectroscopy to probe CO2RR under different electrolyte conditions (KHCO3 + KCl and KOH).
• Investigated the SERS effect up to 100 nm shell thickness.

Main Results:

• Demonstrated the effectiveness of the SERS strategy for CO2RR studies.
• Observed a correlation between the ratio of low-frequency-binding (LFB) and high-frequency-binding (HFB) *CO intermediates and product selectivity.
• Identified that a higher *CO_LFB/*CO_HFB ratio favors C2H4 generation, while abundant *CO_HFB promotes CO formation.

Conclusions:

• The binding characteristics of CO intermediates significantly influence CO2RR product selectivity.
• The SERS technique provides valuable insights into the reaction mechanism of CO2RR on Cu2O.
• Tailoring catalyst properties to control *CO intermediate binding can steer CO2RR towards desired products.