Urea-Functionalized Silver Catalyst toward Efficient and Robust CO₂ Electrolysis with Relieved Reliance on Alkali...

Area of Science:

• Electrochemistry
• Catalysis
• Materials Science

Background:

• Electrochemical CO2 reduction (CO2R) is crucial for sustainable chemical production.
• Membrane electrode assembly (MEA) electrolyzers face challenges in reactivity and durability.
• Silver (Ag) is a key catalyst for CO2R, but its performance can be limited.

Purpose of the Study:

• To develop a novel strategy to enhance the performance of silver catalysts in MEA-type CO2 electrolysis.
• To investigate the effect of urea modification on the reactivity and durability of Ag catalysts.
• To understand the mechanisms behind urea's beneficial effects on CO2R.

Main Methods:

• Modification of the silver catalyst layer with urea.
• Electrochemical testing of membrane electrode assembly (MEA) electrolyzers.
• Experimental and theoretical analysis of catalyst performance and stability.
• Long-term stability tests at high current densities.

Main Results:

• Urea modification significantly improved CO2R promotion and energy efficiency compared to untreated Ag catalysts.
• Urea mitigated alkali cation transport limitations and salt precipitation in the gas diffusion electrode.
• The urea-modified Ag catalyst achieved over 85% faradaic efficiency for CO at 100 mA cm-2 for 200 hours.
• CO selectivity was 1.3 times better and energy efficiency was 2.8-fold better with urea modification.

Conclusions:

• Urea modification is an effective strategy to enhance the reactivity and durability of silver catalysts for CO2 electrolysis.
• This approach offers an alternative method for fabricating catalyst interfaces in MEAs.
• The findings have implications for critical electrochemical applications like CO2 electrolysis and fuel cells.