Achieving High Single-Pass Carbon Conversion Efficiencies in Durable CO₂ Electroreduction in Strong Acids via...

Area of Science:

• Electrochemistry
• Materials Science
• Chemical Engineering

Background:

• Acidic CO2 reduction (CO2 R) is promising for sustainable chemical synthesis.
• Catalyst corrosion in strong acids limits CO2 R performance and durability.
• Hydrogen evolution is a major competing reaction in acidic CO2 R.

Purpose of the Study:

• To develop a method for protecting catalysts during acidic CO2 R.
• To enhance the durability and performance of CO2 R catalysts in strong acids.
• To investigate the role of electrode microstructures in CO2 R.

Main Methods:

• Coating catalysts with an electrically nonconductive nanoporous SiC-Nafion layer.
• Stabilizing a near-neutral pH on catalyst surfaces.
• Applying the coating strategy to SnBi, Ag, and Cu catalysts.
• Fabricating a stratified SiC-Nafion/SnBi/PTFE electrode.

Main Results:

• The SiC-Nafion coating protected catalysts from corrosion in strong acids.
• Near-neutral surface pH was maintained, suppressing hydrogen evolution.
• SnBi, Ag, and Cu catalysts showed high activity and durability over extended operation.
• The stratified electrode achieved constant formic acid production with high carbon and Faradaic efficiencies (>75% and >90%, respectively) at 100 mA cm-2 over 125 h at pH 1.

Conclusions:

• The surface-coating strategy provides effective catalyst protection for durable acidic CO2 R.
• Electrode microstructure is critical for ion diffusion and electrohydrodynamic flow control.
• This approach enables efficient and stable production of formic acid from CO2.