Molecular Engineering of Cation Solvation Structure for Highly Selective Carbon Dioxide Electroreduction

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Selective carbon dioxide electroreduction (CO2 RR) is vital for sustainable chemistry.
• Balancing water activation is key to enhancing CO2 RR selectivity over hydrogen evolution (HER).

Purpose of the Study:

• To develop a molecular engineering strategy for regulating water activation in CO2 RR.
• To improve CO2 RR selectivity by controlling the interface water density and proton supplier content.

Main Methods:

• Utilizing aprotic organic small molecules with high Gutmann donor numbers as solvation shell regulators.
• Investigating the effect of organic molecules on K+ solvation shells and the electrical double layer.
• Employing dimethyl sulfoxide (DMSO) as an additive in a KCl electrolyte (KCl-DMSO-5) with Ag foil electrodes.

Main Results:

• Organic molecules decreased interfacial water density, suppressing HER.
• Weakened O-H bonds in adsorbed water promoted dissociation, enhancing CO2 protonation kinetics.
• Achieved 99.2% CO selectivity and >90.0% Faradaic efficiency for CO (FECO) on Ag foil within -0.75 to -1.15 V vs. RHE.

Conclusions:

• The molecular engineering strategy effectively regulates water activation for selective CO2 RR.
• This approach is extendable to other metal electrodes (Zn, Sn) and organic molecules (e.g., N,N-dimethylformamide).