Carbon Dioxide Electroreduction on Gold without Metal or Organic Cations.

Area of Science:

• Electrochemistry
• Catalysis
• Carbon capture and utilization

Background:

• The electroreduction of carbon dioxide (CO2) to valuable chemicals is crucial for a circular carbon economy.
• Gold (Au) surfaces selectively convert CO2 to CO via the CO2 reduction reaction (CO2RR).
• Cation presence at the electrode-electrolyte interface influences CO2RR catalytic activity.

Purpose of the Study:

• To investigate if CO2 electroreduction to CO can occur on Au in the absence of metal or organic cations.
• To elucidate the mechanism of CO2RR under cation-free conditions.

Main Methods:

• Electrochemical experiments using gold (Au) electrodes in acidic electrolytes.
• Rigorous control to eliminate metal and organic cations.
• Potentiodynamic CO-stripping scans and chromatography-assisted electrolysis for CO detection.
• Computational calculations and spectroelectrochemical analysis.

Main Results:

• CO2 can be electrochemically reduced to CO on Au in cation-free acidic electrolytes.
• Hydronium ions (H3O+) can stabilize the CO2 radical anion (CO2-) intermediate, but require more negative potentials compared to alkali metal cations.
• Reduced interfacial electric field strength in cation-free electrolytes contributes to increased overpotential for CO2RR.

Conclusions:

• CO2 electroreduction to CO on Au is possible without metal or organic cations.
• The mechanism involves stabilization of intermediates by hydronium ions and is influenced by interfacial electric field strength.
• Understanding these factors is key for optimizing CO2RR processes.