Spatial Ion Redistribution Enables Stable Ethylene Synthesis in Acidic CO₂ Electrolysis.

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Electrocatalytic CO2 reduction (eCO2R) under acidic conditions offers advantages but faces challenges in selective multicarbon synthesis due to hydrogen evolution.
• Conventional methods to improve selectivity are limited by steric constraints at high current densities, impacting performance and stability.

Purpose of the Study:

• To develop a novel ion-gated porous overlayer (IGPO) for enhanced eCO2R selectivity and stability under acidic conditions.
• To overcome the limitations of conventional approaches by creating a volumetric ion-management zone.

Main Methods:

• Fabrication of a hierarchical architecture using porous carbon nanocages (PCNs) and polymeric triazine nanocage layers on a Cu catalyst.
• Theoretical modeling to understand ion dynamics and microenvironment modulation.
• Incorporation of single-atom nickel sites for tandem catalysis.

Main Results:

• The IGPO design effectively displaces cation concentration peaks and attenuates proton concentration at the catalytic surface.
• Protonated triazine groups create locally alkaline microenvironments, suppressing hydrogen evolution.
• The optimized electrode achieved 61.1% Faradaic efficiency for ethylene and 86.2% for C2+ products at 400 mA cm-2, with over 220 hours of stable operation.

Conclusions:

• The ion-gated porous overlayer strategy provides a generalizable framework for improving selectivity and stability in eCO2R.
• This approach advances carbon-neutral chemical manufacturing by enabling efficient multicarbon synthesis.