Electrolyte buffering species as oxygen donor shuttles in CO electrooxidation

Area of Science:

• Electrochemistry
• Surface Science
• Catalysis

Background:

• Electrolyte buffering species are known proton donors in hydrogen evolution reactions (HER).
• The role of these species in other electrochemical reactions, like carbon monoxide electrooxidation (COOR), remains less understood.

Purpose of the Study:

• To investigate the role of electrolyte buffering species in CO electrooxidation (COOR).
• To determine if electrolyte species can act as oxygen donors in COOR, influencing reaction kinetics and overpotential.

Main Methods:

• Utilized a gold rotating disk electrode in a model system with fast kinetics and a diffusion-limited regime.
• Performed systematic concentration dependence studies across various buffers.
• Employed attenuated total reflection infrared spectroscopy (ATR-FTIR) to probe the electrode-electrolyte interface.
• Developed models to incorporate solution reaction effects on surface speciation.

Main Results:

• Demonstrated that electrolyte buffering species act as oxygen donor shuttles in COOR.
• Showed that these species lower the reaction overpotential on gold electrodes.
• Observed a similar correlation between electrolyte properties and electrocatalytic activity on platinum electrodes.
• Identified the buffer conjugated base generating hydroxide ions (OH-) through acid-base reactions with water as the key oxygen donor.

Conclusions:

• Electrolyte buffering species play a crucial role in facilitating COOR by acting as oxygen donors.
• The proposed mechanism involves the buffer conjugated base generating OH- ions, which are essential for the reaction.
• This finding has implications for designing electrolytes to optimize COOR efficiency in various electrochemical applications.