Mass transport-dependent in situ Raman detection in CO/CO₂ electrolysis.

Area of Science:

• Electrochemistry
• Spectroscopy
• Catalysis

Background:

• In situ Raman spectroscopy is vital for understanding CO2/CO electroreduction mechanisms.
• Traditional H-type cells can limit mass transport, potentially skewing mechanistic interpretations.
• GDE-type flow cells offer an alternative with improved mass transport characteristics.

Purpose of the Study:

• To systematically compare in situ Raman detection of intermediates during CO2/CO reduction using H-type and GDE-type spectroelectrochemical cells.
• To evaluate the influence of cell configuration on mechanistic understanding derived from Raman signals.
• To determine the critical role of mass transport in accurate in situ Raman analysis of electrochemical reduction.

Main Methods:

• Utilized H-type and GDE-type spectroelectrochemical flow cells for in situ Raman spectroscopy.
• Performed systematic comparisons of CO2 and CO electroreduction experiments.
• Analyzed Raman signals to detect and quantify surface-adsorbed intermediates.

Main Results:

• Cell configuration had minimal impact on CO2 reduction intermediate detection due to CO2's high solubility.
• CO reduction showed significant differences between cell types, with H-type cells exhibiting lower intermediate formation due to mass transport limitations.
• GDE-type flow cells provided distinct and more reliable in situ Raman data for CO reduction.

Conclusions:

• Mass transport limitations in H-type cells significantly affect CO reduction intermediate coverage and Raman signals.
• Accurate mechanistic elucidation of CO electrolysis via in situ Raman requires circumventing mass transport limitations.
• GDE-type flow cells are crucial for reliable in situ Raman studies of CO electroreduction.