Overcoming Low C₂₊ Yield in Acidic CO₂ Electroreduction: Modulating Local Hydrophobicity for Enhanced Performance

Area of Science:

• Electrochemistry
• Catalysis
• Materials Science

Background:

• Electrochemical CO2 reduction (CO2RR) in acidic media offers advantages like stable electrolyte cycling.
• However, hydrogen evolution reaction (HER) and low multi-carbon (C2+) product yields hinder efficient CO2RR in acid.
• Controlling the catalyst's local environment is key to overcoming these challenges.

Purpose of the Study:

• To investigate the impact of local hydrophobicity on acidic CO2RR performance.
• To develop a facile method for tuning catalyst hydrophobicity.
• To enhance CO2RR efficiency, selectivity towards C2+ products, and operational stability in acidic media.

Main Methods:

• Direct electrodeposition was used to finely tune catalyst layer hydrophobicity without additives.
• Electrochemical performance was evaluated in acidic media (pH=2).
• Long-term stability tests were conducted at industrially relevant current densities.

Main Results:

• A highly hydrophobic microenvironment significantly suppressed HER and improved CO2RR performance.
• Faradaic efficiency (FE) for C2+ products reached ~74% on electrodeposited copper in a hydrophobic environment.
• The method demonstrated scalability, achieving ~81% total FE for CO2RR and ~62% FE for C2+ species with commercial copper.
• Stable operation exceeding 50 hours at 300 mA cm-2 was achieved.

Conclusions:

• Interface hydrophobicity plays a crucial role in enhancing acidic CO2RR.
• The developed method is facile, universally applicable, and effective for producing high-value products via CO2RR in acidic media.
• This approach offers a promising pathway for efficient and stable industrial CO2 conversion.