pH-Sensitive and Self-Regenerative Honeycomb Polymer Membrane-Electrode Assembly for CO₂ Reduction: Shifting...

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• The electrochemical carbon dioxide reduction reaction (CO2RR) is crucial for sustainable chemical production.
• Achieving high selectivity for C2 products in CO2RR remains a significant challenge.
• Current methods often struggle with catalyst stability and electrode hydrophobization.

Purpose of the Study:

• To present a versatile honeycomb polymer membrane-electrode assembly (HMEA) for enhanced CO2RR.
• To investigate the role of a pH-sensitive polymer membrane in controlling CO2RR selectivity.
• To demonstrate the stability and reusability of the HMEA system.

Main Methods:

• Fabrication of a honeycomb polymer membrane-electrode assembly (HMEA) using PMMA-b-P4VP.
• Electrochemical characterization of CO2RR using copper and silver foil electrodes within the HMEA.
• Analysis of product selectivity and reaction efficiency under varying potentials.
• Investigation of Cassie-Baxter behavior induced by the polymer membrane.

Main Results:

• The HMEA significantly shifts CO2RR selectivity towards C2 molecules (ethanol, ethylene) at potentials above 0.9 V RHE.
• The polymer membrane's honeycomb structure and pH-sensitivity induce Cassie-Baxter behavior, suppressing hydrogen evolution.
• Selectivity shifts towards formate at lower potentials, and towards CO, formate, and ethanol with silver electrodes.
• The HMEA demonstrates stability and can be restored after 24 hours of operation.

Conclusions:

• The HMEA offers a simple yet effective strategy to control CO2RR selectivity.
• The bio-inspired, pH-sensitive polymer membrane is key to enhancing C2 product formation.
• This versatile HMEA concept shows promise for various electrode materials in CO2RR applications.