Protonation pathway for CO₂ reduction mediated by coordinated H₂O on active sites.

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Electrochemical CO2 reduction is crucial for fuel production but requires understanding water's role.
• The precise influence of water on catalytic sites remains poorly understood.
• Metal-organic frameworks offer precise active sites for mechanistic studies.

Purpose of the Study:

• To investigate the mechanistic role of coordinated water in CO2 electroreduction.
• To elucidate how water influences reaction pathways and product selectivity.
• To leverage bismuth-based metal-organic frameworks for mechanistic insights.

Main Methods:

• Utilizing a bismuth-based metal-organic framework with molecularly precise active sites.
• Conducting in-depth mechanistic studies of electrochemical CO2 reduction.
• Analyzing reaction pathways involving water and CO2 adsorption.

Main Results:

• Coordinated water promotes CO2 adsorption and alleviates proton supply issues.
• A protonated carbonic acid pathway involving surface hydride transfer was identified.
• Achieved 99% selectivity for CO2 reduction to formic acid.
• Obtained a high turnover frequency of 21.1 s^-1.

Conclusions:

• Water plays a critical role in facilitating CO2 adsorption and activation.
• The identified pathway enhances CO2 reduction efficiency and selectivity.
• Metal-organic frameworks are valuable tools for understanding catalytic mechanisms.
• This work advances the design of catalytic systems for CO2 conversion.