Anionic Surfactant-Tailored Interfacial Microenvironment for Boosting Electrochemical CO₂ Reduction

Area of Science:

• Electrochemistry
• Catalysis
• Surface Science

Background:

• Electrolyte composition critically influences the carbon dioxide reduction reaction (CO2RR).
• Designing effective electrolytes for enhanced CO2RR remains a significant challenge.
• Anionic surfactants are explored as potential electrolyte additives.

Purpose of the Study:

• To investigate the use of anionic surfactants, specifically dodecylphosphonic acid (DDPA) and its analogues, as electrolyte additives.
• To tune the interfacial microenvironment for improved CO2RR performance.
• To enhance the selectivity of carbon products in CO2RR.

Main Methods:

• Employing anionic surfactants (DDPA and analogues) as electrolyte additives.
• Utilizing typical commercial catalysts for CO2RR.
• Conducting mechanistic studies to understand the role of DDPA.
• Performing electrochemical measurements in H-type and flow cells.

Main Results:

• DDPA addition significantly enhanced CO2 selectivity for commercial catalysts in neutral and acidic electrolytes.
• Mechanistic studies revealed DDPA restructures the interfacial hydrogen-bond environment, promoting CO2 protonation to CO.
• Faradaic efficiency (FE) of CO increased from 70% to 98% at -1.0 V in an H-type cell.
• Over 90% FE_CO was maintained in a flow cell across a current density range of 50-400 mA cm⁻².
• The strategy proved effective in acidic CO2RR (pH 1.5-3.5).

Conclusions:

• Anionic surfactant-tailored electrolytes offer a promising strategy for enhancing CO2RR.
• DDPA effectively modulates the interfacial water structure, facilitating CO2 reduction to CO.
• This approach provides a versatile method for improving CO2RR selectivity across various conditions, including acidic media.