Efficient Bicarbonate Electrolysis to Formate Enabled via Ionomer Surface Modification in Cation Exchange Membrane...

Area of Science:

• Electrochemistry
• Catalysis
• Carbon Capture and Utilization

Background:

• Electrochemical CO2 reduction (CO2RR) converts CO2 into valuable chemicals like formate.
• Current systems require pure CO2 and are incompatible with direct industrial emissions.
• Bicarbonate electrolysis faces challenges with high voltage and low energy efficiency, especially using bipolar membranes (BPM).

Purpose of the Study:

• To develop an efficient and robust electrochemical system for direct CO2 utilization from point sources.
• To overcome the limitations of existing CO2RR technologies, particularly regarding energy efficiency and feed gas purity.

Main Methods:

• Fabrication of a cation exchange membrane (CEM)-based membrane electrode assembly (MEA).
• Surface modification of a bismuth cathode catalyst using a positively charged ionomer (PiperION).
• Electrochemical testing of the CEM-based MEA under various conditions, including simulated flue gas.

Main Results:

• The CEM-based MEA achieved a formate faradaic efficiency of up to 80%.
• A significant 1.5 V reduction in operating voltage was observed compared to BPM-based MEAs at 300 mA cm−2.
• The system demonstrated excellent tolerance to O2 impurities and maintained high performance with simulated flue gas.

Conclusions:

• The novel CEM-based MEA with a surface-modified bismuth cathode offers a highly efficient pathway for CO2RR.
• This technology enables direct utilization of CO2 from point sources, bypassing the need for costly capture and purification.
• The improved energy efficiency and impurity tolerance make this system a promising solution for industrial CO2 valorization.