Spectro-Electrochemical Insights into Electrocatalytic CO₂ Reduction in Acidic Media through Model Catalyst Design

Area of Science:

• Materials Science and Engineering
• Electrochemistry
• Catalysis

Background:

• Electrocatalytic CO2 reduction (eCO2R) in acidic media is promising for CO2 utilization but suffers from competition with the hydrogen evolution reaction (HER).
• Understanding the complex triphasic electrode processes and electric double layer (EDL) arrangements is crucial for enhancing eCO2R selectivity and efficiency.

Purpose of the Study:

• To investigate the influence of catalyst geometry on competing HER and eCO2R processes under acidic conditions.
• To elucidate the role of EDL structure and proton sources in modulating reaction kinetics.
• To develop strategies for improving acidic eCO2R performance through catalyst design.

Main Methods:

• Fabrication of model catalysts with tailored cavernous parameters.
• In situ/operando spectro-electrochemical techniques including differential electrochemical mass spectrometry, Raman, Infrared spectroscopy, and rotating disk electrode measurements.
• Analysis of geometrically modulated HER and eCO2R kinetics.

Main Results:

• Overcrowded EDLs in confined nanocages hinder eCO2R at high current densities by limiting reaction volume, CO2 supply, and promoting water dissociation.
• Catalyst geometry significantly influences the interplay between HER and eCO2R.
• Optimized mesoporous structures and expanded EDL zones enhance eCO2R performance.

Conclusions:

• Tailoring catalyst geometry is key to spatially regulating mass transport, local chemical environments, and EDL arrangements for efficient acidic eCO2R.
• Achieving near-unity CO Faradaic efficiency over a wide current range and prolonged operation is possible with precisely engineered catalysts.
• This work provides fundamental insights for designing advanced electrocatalysts for sustainable CO2 utilization.