Tailoring Polymeric Binder of Permselective Gas Diffusion Electrode for Low-Concentration CO₂ Electrolysis

Area of Science:

• Electrochemistry
• Materials Science
• Chemical Engineering

Background:

• Electrochemical CO2 reduction (eCO2R) converts industrial CO2 emissions into valuable chemicals.
• Direct electrolysis of low-concentration CO2 streams faces mass transport limitations and low Faradaic efficiency (FE).

Purpose of the Study:

• To develop a gas diffusion electrode with a permselective layer for enhanced CO2 concentration at the catalyst interface.
• To optimize CO2/N2 selectivity and permeability using different polymer matrices with a CO2-philic metal-organic framework.

Main Methods:

• Fabrication of a permselective layer integrating Calgary Framework-20 (CALF-20) within Nafion, polysulfone (PSF), and styrene-ethylene-butylene-styrene polymer matrices.
• Systematic testing of polymer matrices to evaluate CO2/N2 selectivity and permeability.
• Electrochemical performance evaluation, including partial current density and Faradaic efficiency, in a membrane electrode assembly.

Main Results:

• The CALF-20/PSF composite achieved a CO2/N2 selectivity of approximately 40.
• A threefold increase in CO partial current density (jCO of -42.7 mA cm-2) was observed with a 10% CO2 feed compared to unmodified electrodes.
• The optimized electrode maintained a stable FE_CO of approximately 70% for over 20 hours.

Conclusions:

• The CALF-20/PSF permselective layer effectively concentrates CO2, overcoming mass transport limitations.
• Strong interactions between CALF-20 and PSF enhance CO2 transport and electrode durability.
• This technology offers a promising solution for efficient eCO2R from dilute industrial CO2 streams.