Taming the Hydrogen-Mediated Kinetic Switch for Sulfur-Tolerant CO₂ Electroreduction

Area of Science:

• Electrochemistry
• Catalysis
• Environmental Science

Background:

• Direct electrochemical conversion of industrial flue gas is a promising strategy for carbon neutrality.
• Trace sulfur dioxide (SO2) impurities in flue gas rapidly deactivate catalysts, limiting industrial application.
• Existing methods struggle to maintain catalyst stability under high reaction rates required for industrial processes.

Purpose of the Study:

• To develop a novel strategy to mitigate catalyst deactivation caused by SO2 impurities in electrochemical CO2 conversion.
• To enable stable and efficient conversion of CO2 from industrial flue gas into valuable products.
• To investigate the mechanism of impurity tolerance in electrochemical systems.

Main Methods:

• Introduction of a hydrophobic molecular gate strategy to control interfacial water solvation and proton transfer.
• Regulating the water-deficient regime at the catalyst interface to isolate SO2 from reactive sites.
• Pairing the gate strategy with a lattice-strained copper catalyst in a scaled-up membrane electrode assembly (MEA).

Main Results:

• The hydrophobic gate effectively isolated SO2 from hydrogen-mediated reduction pathways.
• Transient water essential for CO2 conversion was preserved, maintaining high catalytic activity.
• A 100 cm2 MEA operated at 20 A for over 120 hours with >56% ethylene (C2H4) Faradaic efficiency in simulated flue gas.

Conclusions:

• The hydrophobic molecular gate strategy successfully decouples impurity transport from catalyst deactivation.
• This approach significantly enhances catalyst stability and durability in the presence of SO2.
• The developed system demonstrates a viable pathway for industrial-scale electrochemical conversion of CO2 from flue gas.