Electrolyte potentials and impedance measurement of polymer electrolyte membrane CO2 reduction electrolyzer

In electrochemical CO2 reduction reactors, polymer electrolyte membrane (PEM) reactors, also known as zero-gap cells, have great potential for achieving significant CO2 reduction. Because these cells have a thin reactor core with a thickness of several hundred micrometers, it is difficult to determine their internal voltage distribution. To determine the anode voltage, ohmic loss in the membrane, and cathode voltage in the PEM reactors, we set three reference electrodes in the reactor and investigated the voltage values obtained from each reference electrode. We demonstrated that the reference electrode in contact with the anion exchange membrane extending to the outside of the cell provides the most reliable voltage. The voltage measured by this reference, combined with the resistance of the exchange membrane obtained through electrochemical impedance spectroscopy, provides a breakdown of the voltage inside the cell.

Automated summary

Polymer electrolyte membrane (PEM) reactors, also known as zero-gap cells, have great potential for significant CO2 reduction in electrochemical CO2 reduction reactors. However, determining the internal voltage distribution in these thin reactor cores is challenging. To address this, we placed three reference electrodes in the reactor and analyzed the voltage values from each electrode to determine the anode voltage, membrane's ohmic loss, and cathode voltage. Our study found that the reference electrode in contact with the anion exchange membrane extending outside the cell provided the most reliable voltage measurement. Combining this voltage with the resistance of the exchange membrane obtained through electrochemical impedance spectroscopy allowed us to breakdown the voltage distribution inside the cell.